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).

examples/sample-app/spec.ts

@@ -1,62 +1,102 @@
 import {
-  extract,
-  always,
-  actions,
-  weighted,
-  Tap,
   InputText,
-  taps,
+  Tap,
+  actions,
+  always,
+  eventually,
+  extract,
+  from,
+  next,
+  now,
+  pressKey,
   swipes,
+  taps,
+  waitOnce,
+  weighted,
 } from "@uatu/spec";
+import { noUncaughtExceptions } from "@uatu/spec/defaults/properties";
 
 // ── Snapshot extractors (fed by SampleApplication.kt) ──────────
-// See ./android/src/main/kotlin/dev/uatu/sample/SampleApplication.kt
-const clickCount = extract<number>(
-  (state) => (state.snapshots.click_count as number) ?? 0,
+const loggedIn = extract<boolean>(
+  (state) => (state.snapshots.logged_in as boolean) ?? false,
 );
-const username = extract<string>(
-  (state) => (state.snapshots.username as string) ?? "",
+const route = extract<string>(
+  (state) => (state.snapshots.route as string) ?? "",
+);
+const accountCount = extract<number>(
+  (state) => (state.snapshots.account_count as number) ?? 0,
 );
 
 // ── UI elements ────────────────────────────────────────────────
-const clickButton = extract((state) => state.ax.find("text:Click me"));
-const resetButton = extract((state) => state.ax.find("text:Reset"));
-const usernameField = extract((state) => state.ax.find("desc:username_field"));
+const phoneField = extract((state) => state.ax.find("desc:phone_field"));
+const continueButton = extract((state) => state.ax.find("text:Continue"));
+const addAccountButton = extract((state) => state.ax.find("text:Add account"));
+const nameField = extract((state) => state.ax.find("desc:account_name"));
+const createButton = extract((state) => state.ax.find("text:Create"));
 
 // ── Properties ─────────────────────────────────────────────────
+// accountCountNonNegative: the trivial safety property.
+const accountCountNonNegative = always(() => accountCount.current >= 0);
+
+// addAccountAdvances: once we land on add-account, the next step must be on
+// a different screen. Exercises now(x).implies(next(y)).
+const addAccountAdvances = always(
+  now(() => route.current === "add-account").implies(
+    next(() => route.current !== "add-account"),
+  ),
+);
+
+// eventuallyLoggedIn: within 30 seconds of the run starting, we expect to
+// reach home. Exercises eventually(p).within(n, unit).
+const eventuallyLoggedIn = eventually(() => loggedIn.current).within(
+  30,
+  "seconds",
+);
+
 export const properties = {
-  clickCountNonNegative: always(() => clickCount.current >= 0),
-  clickCountNeverDecreases: always(() => {
-    const previous = clickCount.previous;
-    return previous === undefined || clickCount.current >= previous;
-  }),
-  usernameNeverShrinks: always(() => {
-    const previous = username.previous;
-    return previous === undefined || username.current.length >= previous.length;
-  }),
+  accountCountNonNegative,
+  addAccountAdvances,
+  eventuallyLoggedIn,
+  noUncaughtExceptions,
 };
 
 // ── Actions ────────────────────────────────────────────────────
-const tapClickMe = actions(() => {
-  return clickButton.current ? [Tap({ on: clickButton.current })] : [];
+// Sampling: random phone numbers for the login screen.
+const phoneSampler = from(["+919876543210", "+15555550100", "+442071234567"]);
+
+const typePhone = actions(() => {
+  const field = phoneField.current;
+  if (!field) return [];
+  return [InputText({ into: field, text: phoneSampler.generate() })];
 });
 
-const typeUsername = actions(() => {
-  return usernameField.current
-    ? [InputText({ into: usernameField.current, text: "alice" })]
-    : [];
-});
+const tapContinue = actions(() =>
+  continueButton.current ? [Tap({ on: continueButton.current })] : [],
+);
+const tapAddAccount = actions(() =>
+  addAccountButton.current ? [Tap({ on: addAccountButton.current })] : [],
+);
 
-const tapReset = actions(() => {
-  return resetButton.current ? [Tap({ on: resetButton.current })] : [];
+const nameSampler = from(["Alice", "Bob", "Charlie", "Dana"]);
+const fillName = actions(() => {
+  const field = nameField.current;
+  if (!field) return [];
+  return [InputText({ into: field, text: nameSampler.generate() })];
 });
+const tapCreate = actions(() =>
+  createButton.current ? [Tap({ on: createButton.current })] : [],
+);
 
 export const actionsRoot = weighted(
-  [50, tapClickMe],
-  [20, typeUsername],
-  [30, tapReset],
-  [5, taps],
-  [2, swipes],
+  [30, typePhone],
+  [30, tapContinue],
+  [20, tapAddAccount],
+  [20, fillName],
+  [20, tapCreate],
+  [10, taps],
+  [5, swipes],
+  [5, waitOnce],
+  [5, pressKey],
 );
 
 (globalThis as { actions?: unknown; properties?: unknown }).actions = actionsRoot;