docs: P0's iris half done -- bench feature, emulator smoke run, APK

RUST.md's P0 box gets the iris-half account: the fixture, the scroll/stream
mechanism, the report fields, build commands (all clean), packaging (no
cargo xtask apk yet, so a new Gradle release build type on top of cargo
ndk), and the emulator smoke run's report next to Compose's own. Used a
second, differently-named AVD rather than contend with the session already
on this checkout's own emulator.

DECISIONS.md's P0 entry gets a matching summary bullet. IRIS.md records
AndroidAppState::platform_ready. IRIS_TODO.md notes the one gap found:
no read-only selectable text primitive, so the bench report's TextEdit
picks up a keyboard on tap it has nothing to type into.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/DECISIONS.md

@@ -18,6 +18,25 @@ marked **DEFERRED** are ones the agent chose not to decide alone.
   flagged here because it is the first half of something Iris explicitly
   asked to see before P1.
 
+- **P0's iris half is also built and smoke-tested on the emulator,
+  2026-09-05.** A new `bench` Cargo feature on `iris-android-app`, on top
+  of `transcript-screen`: the same checked-in fixture (`include_str!`, no
+  asset pipeline needed), the same 24-swipe scroll loop animated through
+  `List::scroll` and the same 400-event/20s streaming phase through
+  `fold_event`, "Run benchmark"/"Copy report" as named accessible
+  controls, and the same three added report fields (process CPU time,
+  peak RSS, battery current) via direct JNI calls
+  (`bench_jni.rs::PlatformHandle`) since `android_view` has no
+  `BatteryManager`/`ClipboardManager` wrapper of its own. One small public
+  API addition to get there: `AndroidAppState::platform_ready` (`IRIS.md`),
+  a default-no-op lifecycle hook handing an implementor a `JavaVM` +
+  `GlobalRef` it can call Java through from any thread. Packaged with a
+  new `release` build type on `iris-android-app`'s own Gradle project
+  (there was previously only `debug`), signed with the same key
+  `app/build-apk.sh` generates. Smoke run and the full report are in
+  RUST.md's P0 box; not attempted this pass: the real on-phone runs and
+  Iris's pass/fail call, which is the actual gate.
+
 - **The intermittent touch-scroll dropout is root-caused and fixed: a
   missed `ACTION_DOWN` hit-test, not the previously-suspected coalesced
   first `ACTION_MOVE`.** Diagnosed by temporary logcat tracing of every