feat: LTL operators, sampling, and default generators (#17)

* feat(ltl): add Now/Next/Eventually/Implies/Or/And/Not formulas

Replace the fold-with-latch evaluator with a residual-formula reducer.
Each Observe() instantiates a fresh obligation from the root (stripping
an outer Always), reduces each pending obligation against current state,
latches Violated on first failure, and surfaces Pending verdicts for
deferred obligations. Existing Always/Pure/Thunk tests continue to pass.

* feat(ltl): support relative duration for eventually().within()

* feat(proto): add Swipe, PressKey, RecentLogs RPCs

* feat(verifier,runner): formula handles, new action kinds, rich state

- verifier: add formula-spec registry; bindNow/bindNext/bindEventually with
  chainable .implies/.or/.and/.not and .within(n,unit) on eventually; bindFrom
  for uniform sampling. bindAlways keeps accepting plain predicates.
- verifier: store lastTree, lastAction, step time, logs, exceptions on the
  Verifier; SnapshotInput replaces the (snapshots, tree) pair. stateObject now
  produces state.lastAction/time/logs/exceptions matching the TS State type.
- verifier: make taps/swipes/waitOnce/pressKey built-in generators actually
  fire; taps picks a clickable, enabled element from the last hierarchy.
- agent: add exceptions field to Message wire format.
- driver: add Swipe/PressKey/RecentLogs to Driver interface; wire maestro
  client and mock driver. LogEntry exposed for runner consumption.
- runner: apply Swipe/PressKey/Wait actions; collect logcat and exceptions;
  pass lastAction and step time into PushSnapshot.

* feat(spec-api): LTL operators, new actions, richer State

- ltl.ts exports now/next/eventually; always overload accepts a Formula
- types.ts: Formula gains implies/or/and/not; EventuallyFormula adds .within;
  State gains lastAction/time/logs/exceptions; Swipe/PressKey/Wait action types
- actions.ts: Swipe/PressKey/Wait/from constructors; waitOnce + pressKey
  default generators
- tests exercise the chaining, sampling, and new actions through a recorded
  fake runtime

* feat(sidecar): add swipe, pressKey, recentLogs RPC handlers

* feat(sdk-android): capture uncaught exceptions

Install a default uncaught handler on Uatu.start, chained with any
existing handler so Android's crash reporter still runs. Expose
Uatu.reportError for callers to forward caught throwables. A bounded
circular buffer (default 50) drains into each STATE message's new
exceptions field. Protocol.kt serializes/deserializes the field,
matching the Go wire format added to internal/agent/protocol.go.

* feat(spec-api): add @uatu/spec/defaults/properties bundle

* feat(sample-app): exercise new LTL operators + defaults

spec.ts now imports eventually/next/now/from from @uatu/spec and
noUncaughtExceptions from @uatu/spec/defaults/properties. It declares
three properties that exercise the new surface:

- accountCountNonNegative: plain always() safety
- addAccountAdvances: always(now(x).implies(next(y)))
- eventuallyLoggedIn: eventually(p).within(30, "seconds")
- noUncaughtExceptions: imported default

The weighted actions root uses from() for random phone/name sampling
and entries for taps/swipes/waitOnce/pressKey built-ins.

SampleApplication gains a debug hook gated on the system property
uatu.inject_error so the e2e run can synthesize an Uatu.reportError and
verify noUncaughtExceptions violates.

cmd/uatu/test_run.go adds a subpath alias so specs importing
"@uatu/spec/defaults/properties" resolve against the in-tree source
when running from the uatu checkout. The spec-integration tests swap
the old click-counter fixtures for the new login hierarchy.

* feat(trace): record swipe/key/wait details + exceptions

trace.Step gains an Exceptions array so the trace captures the
class/message/stackTrace for each SDK-reported throwable in a step.
trace.Action gains FromX/FromY/ToX/ToY/Key/DurationMillis so the full
payload of Swipe/PressKey/Wait actions is visible in trace.jsonl.

sample-app's debug error hook now gates on ApplicationInfo.DEBUGGABLE
instead of a system property (adb setprop fails on non-rooted
emulators).

internal/verifier/marshal.go

@@ -3,6 +3,7 @@ package verifier
 import (
 	"encoding/json"
 	"fmt"
+	"time"
 
 	"github.com/dop251/goja"
 
@@ -12,13 +13,23 @@ import (
 // Snapshots is the per-step extractor output forwarded by the SDK.
 type Snapshots map[string]json.RawMessage
 
-// stateObject builds a JS-side `{ snapshots, ax }` matching the State type
-// from pkg/spec-api. ax is backed by the parsed uiautomator hierarchy when
-// one is provided.
-func stateObject(runtime *goja.Runtime, snapshots Snapshots, tree *hierarchy.Tree) (*goja.Object, error) {
+type stateInput struct {
+	snapshots  Snapshots
+	tree       *hierarchy.Tree
+	lastAction *Action
+	stepTime   time.Time
+	runStart   time.Time
+	logs       []LogEntry
+	exceptions []Exception
+}
+
+// stateObject builds the JS-side `state` object matching the State type from
+// pkg/spec-api. Fields beyond snapshots/ax are included when the caller
+// populated them on stateInput.
+func stateObject(runtime *goja.Runtime, input stateInput) (*goja.Object, error) {
 	state := runtime.NewObject()
 	snapshotsObject := runtime.NewObject()
-	for key, raw := range snapshots {
+	for key, raw := range input.snapshots {
 		value, err := jsonToJSValue(runtime, raw)
 		if err != nil {
 			return nil, fmt.Errorf("snapshot %q: %w", key, err)
@@ -30,7 +41,19 @@ func stateObject(runtime *goja.Runtime, snapshots Snapshots, tree *hierarchy.Tre
 	if err := state.Set("snapshots", snapshotsObject); err != nil {
 		return nil, err
 	}
-	if err := state.Set("ax", accessibilityObject(runtime, tree)); err != nil {
+	if err := state.Set("ax", accessibilityObject(runtime, input.tree)); err != nil {
+		return nil, err
+	}
+	if err := state.Set("lastAction", lastActionObject(runtime, input.lastAction)); err != nil {
+		return nil, err
+	}
+	if err := state.Set("time", runtimeMillis(input.stepTime, input.runStart)); err != nil {
+		return nil, err
+	}
+	if err := state.Set("logs", logsArray(runtime, input.logs)); err != nil {
+		return nil, err
+	}
+	if err := state.Set("exceptions", exceptionsArray(runtime, input.exceptions)); err != nil {
 		return nil, err
 	}
 	return state, nil
@@ -88,6 +111,74 @@ func elementObject(runtime *goja.Runtime, element *hierarchy.Element, selector s
 	return object
 }
 
+func lastActionObject(runtime *goja.Runtime, action *Action) goja.Value {
+	if action == nil {
+		return goja.Null()
+	}
+	object := runtime.NewObject()
+	_ = object.Set("kind", string(action.Kind))
+	if action.On != "" {
+		_ = object.Set("on", action.On)
+	}
+	if action.Text != "" {
+		_ = object.Set("text", action.Text)
+	}
+	switch action.Kind {
+	case ActionKindSwipe:
+		from := runtime.NewObject()
+		_ = from.Set("x", action.FromX)
+		_ = from.Set("y", action.FromY)
+		to := runtime.NewObject()
+		_ = to.Set("x", action.ToX)
+		_ = to.Set("y", action.ToY)
+		_ = object.Set("from", from)
+		_ = object.Set("to", to)
+		if action.DurationMillis > 0 {
+			_ = object.Set("durationMillis", action.DurationMillis)
+		}
+	case ActionKindPressKey:
+		_ = object.Set("key", action.Key)
+	case ActionKindWait:
+		_ = object.Set("durationMillis", action.DurationMillis)
+	}
+	return object
+}
+
+func runtimeMillis(stepTime, runStart time.Time) int64 {
+	if stepTime.IsZero() || runStart.IsZero() {
+		return 0
+	}
+	return stepTime.Sub(runStart).Milliseconds()
+}
+
+func logsArray(runtime *goja.Runtime, logs []LogEntry) *goja.Object {
+	array := runtime.NewArray()
+	for index, entry := range logs {
+		item := runtime.NewObject()
+		_ = item.Set("unixMillis", entry.UnixMillis)
+		_ = item.Set("level", entry.Level)
+		_ = item.Set("tag", entry.Tag)
+		_ = item.Set("message", entry.Message)
+		_ = array.Set(fmt.Sprintf("%d", index), item)
+	}
+	return array
+}
+
+func exceptionsArray(runtime *goja.Runtime, exceptions []Exception) *goja.Object {
+	array := runtime.NewArray()
+	for index, exception := range exceptions {
+		item := runtime.NewObject()
+		_ = item.Set("class", exception.Class)
+		_ = item.Set("message", exception.Message)
+		_ = item.Set("stackTrace", exception.StackTrace)
+		if exception.UnixMillis > 0 {
+			_ = item.Set("unixMillis", exception.UnixMillis)
+		}
+		_ = array.Set(fmt.Sprintf("%d", index), item)
+	}
+	return array
+}
+
 func jsonToJSValue(runtime *goja.Runtime, raw json.RawMessage) (goja.Value, error) {
 	if len(raw) == 0 {
 		return goja.Undefined(), nil
@@ -99,7 +190,7 @@ func jsonToJSValue(runtime *goja.Runtime, raw json.RawMessage) (goja.Value, erro
 	return runtime.ToValue(generic), nil
 }
 
-// jsValueToAction converts a JS-side {kind, on?, into?, text?} into a Go Action.
+// jsValueToAction converts a JS-side action object into a Go Action.
 func jsValueToAction(runtime *goja.Runtime, value goja.Value) (Action, error) {
 	if value == nil || goja.IsNull(value) || goja.IsUndefined(value) {
 		return Action{}, fmt.Errorf("nil action")
@@ -120,11 +211,60 @@ func jsValueToAction(runtime *goja.Runtime, value goja.Value) (Action, error) {
 		text := object.Get("text")
 		x, y := coordinatesOf(runtime, into)
 		return Action{Kind: ActionKindInputText, On: selectorOf(runtime, into), Text: stringOf(text), X: x, Y: y}, nil
+	case "Swipe":
+		from := object.Get("from")
+		to := object.Get("to")
+		fromX, fromY := coordinatesOf(runtime, from)
+		toX, toY := coordinatesOf(runtime, to)
+		if fromX == 0 && fromY == 0 {
+			fromX, fromY = pointCoordinates(runtime, from)
+		}
+		if toX == 0 && toY == 0 {
+			toX, toY = pointCoordinates(runtime, to)
+		}
+		return Action{
+			Kind:           ActionKindSwipe,
+			FromX:          fromX,
+			FromY:          fromY,
+			ToX:            toX,
+			ToY:            toY,
+			DurationMillis: intField(object, "durationMillis"),
+		}, nil
+	case "PressKey":
+		return Action{Kind: ActionKindPressKey, Key: stringOf(object.Get("key"))}, nil
+	case "Wait":
+		return Action{Kind: ActionKindWait, DurationMillis: intField(object, "durationMillis")}, nil
 	default:
 		return Action{}, fmt.Errorf("unknown action kind %q", kind)
 	}
 }
 
+// pointCoordinates reads a plain {x, y} literal (not an AX element), which is
+// how Swipe endpoints are commonly expressed in specs.
+func pointCoordinates(runtime *goja.Runtime, value goja.Value) (int, int) {
+	if value == nil || goja.IsNull(value) || goja.IsUndefined(value) {
+		return 0, 0
+	}
+	object := value.ToObject(runtime)
+	if object == nil {
+		return 0, 0
+	}
+	x := object.Get("x")
+	y := object.Get("y")
+	if x == nil || y == nil {
+		return 0, 0
+	}
+	return int(x.ToInteger()), int(y.ToInteger())
+}
+
+func intField(object *goja.Object, name string) int {
+	value := object.Get(name)
+	if value == nil || goja.IsUndefined(value) || goja.IsNull(value) {
+		return 0
+	}
+	return int(value.ToInteger())
+}
+
 func selectorOf(runtime *goja.Runtime, value goja.Value) string {
 	if value == nil || goja.IsNull(value) || goja.IsUndefined(value) {
 		return ""