feat(examples): add sample-app spec

Introduce examples/sample-app/spec.ts — a minimal property-based spec that
taps the sample app's "Click me" button and asserts click_count is
monotonic. Bundle-check and the trace writer test now reference the new
path.

examples/sample-app/spec.ts

@@ -0,0 +1,45 @@
+import {
+  extract,
+  always,
+  actions,
+  weighted,
+  Tap,
+  taps,
+  swipes,
+} from "@uatu/spec";
+
+// ── Snapshot extractors (fed by SampleApplication.kt) ──────────
+// See ./android/src/main/kotlin/dev/uatu/sample/SampleApplication.kt
+const appState = extract<string>(
+  (state) => (state.snapshots.app_state as string) ?? "",
+);
+const clickCount = extract<number>(
+  (state) => (state.snapshots.click_count as number) ?? 0,
+);
+
+// ── UI elements ────────────────────────────────────────────────
+const clickButton = extract((state) => state.ax.find("text:Click me"));
+
+// ── Properties ─────────────────────────────────────────────────
+export const properties = {
+  appIsRunning: always(() => appState.current === "running"),
+  clickCountNonNegative: always(() => clickCount.current >= 0),
+  clickCountNeverDecreases: always(() => {
+    const previous = clickCount.previous;
+    return previous === undefined || clickCount.current >= previous;
+  }),
+};
+
+// ── Actions ────────────────────────────────────────────────────
+const tapClickMe = actions(() => {
+  return clickButton.current ? [Tap({ on: clickButton.current })] : [];
+});
+
+export const actionsRoot = weighted(
+  [100, tapClickMe],
+  [10, taps],
+  [2, swipes],
+);
+
+(globalThis as { actions?: unknown; properties?: unknown }).actions = actionsRoot;
+(globalThis as { properties?: unknown }).properties = properties;