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/IRIS_TODO.md

@@ -82,6 +82,18 @@ order and what "done" looks like. Tick and date them in place.
   were exactly the same root cause measured two different ways. Frame 2
   now reports 0 (see the numbers above); not a separate fix.
 
+- [ ] **A read-only text display has no widget of its own — P0's bench
+  report area is a `TextEdit` standing in for one (2026-09-05).** The only
+  way to get selectable text on screen today is `.editable(...)` plus
+  `.attr::<Selectable>(())` (`Selectable` is only implemented for
+  `TextEdit`, `iris/src/attr.rs`), which also makes the field focusable —
+  tapping the bench report opens the soft keyboard over text nothing lets
+  you type into. Harmless for a bench-only debug screen (not fixed this
+  pass), but a real "selectable, not editable" text primitive would
+  remove the keyboard side effect and is worth having before another
+  screen wants the same thing (P1's own transcript rows already read
+  their content from a `TextEdit` for the same reason).
+
 ## Build
 
 - [x] **Benchmarks**, not unit tests, run on demand (2026-09-05; a