iris is the framework alone; the app is one crate in app-rust/

Iris: "the organization of the rust rewrite is a mess right now... there
shouldn't be anything related to the app inside of iris. Iris is supposed
to be the UI framework alone." And, on the crate count: "I'm confused why
the app only code needs more than one crate though."

Nine cargo workspaces become three, and the port's project code -- which
sat in five places, four of them inside the framework -- becomes one crate,
`ai-app`, in `app-rust/`:

  client-core                -> app-rust/src/client
  iris/transcript-ui         -> app-rust/src/ui
  iris/transcript-fixture    -> app-rust/src/ui/fixture.rs + tests/ + touch/
  iris/desktop-app           -> app-rust/src/desktop + src/bin_desktop.rs
  iris/android-app           -> app-rust/src/android + android-project/
  android-shell              -> app-rust/src/shell

iris/ keeps core, macro, the iris crate, tabs-ui and rig-input, and now
mentions no session, transcript, setup or server anywhere.

Only two of the old splits had a reason that survived reading. event-model
stays a crate at the repo root because server/ depends on it too, so a
crate is what makes the backend and the app agree by construction. The two
Android .so names looked like a hard constraint -- a package produces one
library artifact -- until P2 turned out to already plan merging those two
Android apps into one; both faces now come out of libai_app.so, picked
apart by features so `--no-default-features --features shell` keeps wgpu,
parley and iris out of the Compose app's APK. docs/RUST.md's "One app
crate" has the rest, including what each remaining feature is for.

DECISIONS.md and SUBAGENTS.md move into docs/ with everything else.

Verified: ./run-tests.sh and `cd iris && cargo test` green, clippy and fmt
clean in all five workspaces, `cargo ndk -t x86_64` links libai_app.so,
build-apk.sh produces an APK that installs and launches on this checkout's
emulator (Gl ... virgl, as expected), and the phone-sized headless
screenshot renders the transcript unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/default/input.rs

@@ -1,4 +1,10 @@
+// `CursorState::time` is the sample's own time on every backend. winit
+// carries no timestamp on a pointer event, so the moment it is handed to
+// us is the closest measurement available here -- which is also what the
+// drag code used to do for itself with `Instant::now()`, before Android's
+// batched samples made the difference matter (see `sense::CursorState`).
 use crate::prelude::*;
+use std::time::Instant;
 use winit::{
     event::{MouseButton, MouseScrollDelta, WindowEvent},
     keyboard::{Key, NamedKey},
@@ -11,13 +17,19 @@ pub struct Input {
 }
 
 impl Input {
+    /// winit's pointer coordinates are physical pixels, which is the
+    /// space the whole tree is laid out and hit-tested in -- see
+    /// `default::content_scale`. Nothing is converted here; `dp(...)`
+    /// resolves against the density at layout time instead.
     pub fn event(&mut self, event: &WindowEvent) -> bool {
         match event {
             WindowEvent::CursorMoved { position, .. } => {
                 self.cursor.pos = Vec2::new(position.x as f32, position.y as f32);
                 self.cursor.exists = true;
+                self.cursor.time = Instant::now();
             }
             WindowEvent::MouseInput { state, button, .. } => {
+                self.cursor.time = Instant::now();
                 let buttons = &mut self.cursor.buttons;
                 let pressed = state.is_pressed();
                 match button {
@@ -37,6 +49,7 @@ impl Input {
                     delta.y = 0.0;
                 }
                 self.cursor.scroll_delta = delta;
+                self.cursor.time = Instant::now();
             }
             WindowEvent::CursorLeft { .. } => {
                 self.cursor.exists = false;
@@ -67,9 +80,12 @@ impl Input {
 }
 
 impl DefaultUiState {
+    /// Physical pixels, matching `WindowEvent::Resized` (what
+    /// `UiRenderState::resize` is given) and the swapchain -- see
+    /// `default::content_scale`.
     pub fn window_size(&self) -> Vec2 {
         let size = self.renderer.window().inner_size();
-        (size.width, size.height).into()
+        Vec2::new(size.width as f32, size.height as f32)
     }
 
     pub fn cursor_state(&self) -> &CursorState {