iris: FrameReport, a per-frame wall-time report of iris's own render path

dumpsys gfxinfo cannot see a SurfaceView's own GPU-drawn frames at all
(RUST.md's I5 box), so iris needs its own equivalent of Compose's
render-report button before item 3 of the recommendation can be decided
by a number. FrameReport (iris/core/src/render/frame_report.rs) records
each frame's wall time -- from render()'s redraw start to after
queue.submit + present() -- into a fixed 4096-entry ring, and reports
total frames, janky % (>16.7ms, gfxinfo's own budget), P50/P90/P99 and
the worst. Wired into AndroidUiState and android/view.rs's render(), and
exposed as two named controls ("Frame report", "Reset frame report") on
iris-android-app's transcript screen, logged under the crate's fixed tag
so a script can grep "iris frame report" the way transcript-bench.sh
greps "ai-app render report".

6 new unit tests for the ring/percentile math. cargo fmt/clippy/test
--workspace clean; cargo ndk (iris, transcript-ui, and
iris-android-app --features transcript-screen) all clean.

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

iris/android-app/src/transcript_client.rs

@@ -44,6 +44,12 @@ mod pinned {
 
 pub struct TranscriptClient {
     ui_state: AndroidUiState,
+    /// The screen's own content -- everything under the fixed
+    /// [`frame_report_controls`] bar, which is built once (`new`, below)
+    /// and never touched by `show_message`/`rebuild_transcript`'s own
+    /// `set` calls the way `desktop-app`'s `transcript_ptr` isn't touched
+    /// by rebuilding the session list beside it.
+    content: WeakWidget<WidgetPtr>,
     screen: Option<transcript_ui::TranscriptScreen>,
     /// The folded transcript as of the last rebuild -- kept here (not
     /// re-derived) for the same reason `desktop-app`'s `Client::items`
@@ -94,13 +100,76 @@ fn placeholder<Rsc: HasEvents>(rsc: &mut Rsc, message: &str) -> StrongWidget {
         .any()
 }
 
+/// The two named controls RUST.md's I5 box ("Measurements taken" (b))
+/// drives by name over `ui-trace`, e.g. `ui-trace record --do "tap 'Frame
+/// report'"`. `dumpsys gfxinfo` cannot see this screen's own GPU-drawn
+/// frames at all -- this is the screen's own equivalent of the Compose
+/// app's "Copy render timings" control, logged rather than clipboarded
+/// (no clipboard wiring exists here) under this crate's own fixed
+/// `android_logger` tag (`iris-android-app`, `lib.rs`'s `JNI_OnLoad`),
+/// grep-able on the fixed string `"iris frame report"` the way
+/// `transcript-bench.sh` greps `"ai-app render report"`.
+fn frame_report_controls(rsc: &mut AndroidRsc<TranscriptClient>) -> WeakWidget {
+    type Rsc = AndroidRsc<TranscriptClient>;
+    let report_rect = rect(Color::rgb(50, 50, 60))
+        .on(
+            CursorSense::click(),
+            |ctx: EventIdCtx<'_, Rsc, _, _>, _rsc: &mut Rsc| match ctx
+                .state
+                .android_state()
+                .frame_report
+                .report()
+            {
+                Some(stats) => log::info!("iris frame report: {stats}"),
+                None => log::info!(
+                    "iris frame report: no frames recorded -- scroll first, then press this"
+                ),
+            },
+        )
+        .label("Frame report");
+    let report = (
+        report_rect,
+        wtext("Frame report").size(18).text_align(Align::CENTER),
+    )
+        .stack()
+        .pad(8)
+        .add(rsc);
+
+    let reset_rect = rect(Color::rgb(70, 40, 40))
+        .on(
+            CursorSense::click(),
+            |ctx: EventIdCtx<'_, Rsc, _, _>, _rsc: &mut Rsc| {
+                ctx.state.android_state_mut().frame_report.reset();
+                log::info!("iris frame report: reset");
+            },
+        )
+        .label("Reset frame report");
+    let reset = (
+        reset_rect,
+        wtext("Reset").size(18).text_align(Align::CENTER),
+    )
+        .stack()
+        .pad(8)
+        .add(rsc);
+
+    (report, reset).span(Dir::RIGHT).height(56).add(rsc)
+}
+
 impl AndroidAppState for TranscriptClient {
     fn new(mut ui_state: AndroidUiState, rsc: &mut AndroidRsc<Self>) -> Self {
+        let content = WidgetPtr::new().add(rsc);
         let loading = placeholder(rsc, "Loading sessions...");
-        ui_state.set_root(loading);
+        content(rsc).set(loading);
+
+        let tree = (frame_report_controls(rsc), content.height(rest(1)))
+            .span(Dir::DOWN)
+            .add_strong(rsc)
+            .any();
+        ui_state.set_root(tree);
 
         let mut client = Self {
             ui_state,
+            content,
             screen: None,
             items: Vec::new(),
             session_id: None,
@@ -120,7 +189,7 @@ impl AndroidAppState for TranscriptClient {
 impl TranscriptClient {
     fn show_message(&mut self, rsc: &mut AndroidRsc<Self>, message: &str) {
         let widget = placeholder(rsc, message);
-        self.android_state_mut().set_root(widget);
+        (self.content)(rsc).set(widget);
         self.screen = None;
     }
 
@@ -286,7 +355,7 @@ impl TranscriptClient {
             });
         }
 
-        self.android_state_mut().set_root(tree);
+        (self.content)(rsc).set(tree);
         self.screen = Some(screen);
     }