iris android-app: Benchmark v2 -- fling, type and keyboard phases

Implements RUST.md's "Benchmark v2" spec in bench_client.rs: fling (8 out
+ 8 back at 12,000px/s through List::fling, waits for !is_scrolling()
capped 3s, reports travel as row index + offset via List's new
anchor_position_display), stream (unchanged), type (the 600-char P0
constant, one char per 50ms into the composer's real TextEdit via .set(),
then deleted), and keyboard (5 show/hide cycles via bench_jni.rs's new
InputMethodManager calls, confirmed from on_insets_changed's real
ime_bottom transitions rather than assumed from the JNI call returning).

FrameReport gained mark_phase/phase_stats/late_at_hz (iris/core) so the
report can show a per-phase block (frames, late%, p50/p90/p99, worst)
against the display's real refresh rate (bench_jni's new
refresh_rate_hz), matching the shape docs/bench/compose-phone-v2 uses.
RING_CAPACITY bumped 4096->16384 since a full v2 run is ~3,000+ frames.

Found and fixed a real deadlock while wiring this up: read_from_state
(a new helper that gets a value back out of a spawned task's ctx.update,
which has no return channel of its own) only worked for its first call in
a chain, because nothing called redraw.request_redraw() after enqueueing
later ones -- nothing then drains the task channel to run them. Every
call now triggers its own redraw.

Verified end to end on this checkout's x86_64 emulator (force-gles, cold
boot): fling/stream/type all report populated phase blocks; keyboard's
show never got a real on_insets_changed confirmation this run (see
follow-up work). Full report and travel numbers go in RUST.md's P0 box
next.

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

iris/android-app/run-bench.sh

@@ -46,10 +46,13 @@ adb -s "$SERIAL" shell am start -n "$PKG/dev.iris.android.demo.MainActivity" >/d
 
 ui-trace record -s "$SERIAL" -d 3000 --do "tap 'Run benchmark'" -o /tmp/run-bench-tap.txt >/dev/null
 
-# Poll for the report line rather than a fixed sleep -- the run itself is a
-# fixed script (24 swipes + a 20s streaming phase) but device speed varies.
+# Poll for the report line rather than a fixed sleep -- the run itself is
+# a fixed script (RUST.md's "Benchmark v2": 16 flings, a 20s streaming
+# phase, ~61s of typing, 10s of keyboard toggles, roughly 2.5 minutes end
+# to end) but device speed varies. 260s cap rather than v1's 90s -- v2 is
+# a longer script than v1's swipe-loop-only run.
 i=0
-while [ "$i" -lt 90 ]; do
+while [ "$i" -lt 260 ]; do
     LINE=$(adb -s "$SERIAL" logcat -d -s iris-android-app:I 2>/dev/null | grep "iris bench report:" || true)
     if [ -n "$LINE" ]; then
         break
@@ -58,7 +61,9 @@ while [ "$i" -lt 90 ]; do
     sleep 1
 done
 if [ -z "$LINE" ]; then
-    echo "run-bench.sh: no report after 90s -- check logcat by hand" >&2
+    echo "run-bench.sh: no report after 260s -- check logcat by hand" >&2
     exit 1
 fi
-adb -s "$SERIAL" logcat -d -s iris-android-app:I | grep -A 6 "iris bench report:"
+# -A 60 rather than v1's -A 6 -- v2's report has a per-phase block (four
+# phases, four lines each) on top of the frames/bench sections v1 had.
+adb -s "$SERIAL" logcat -d -s iris-android-app:I | grep -A 60 "iris bench report:"