iris/android: the composer's launch position was the bench report pane, plus surface/insets lifecycle logging

The empty benchmark-report TextEdit held .height(rest(1)) beside
content.height(rest(2)), so it reserved a third of the window at every
launch and pushed the composer two thirds down -- Iris's 11:39 phone
report. It is sized to its content now, capped and scrollable, and sits
above the transcript rather than under the composer.

New log::info! lines for one insets change, one surface_changed, one
renderer build and one surface_destroyed, each with the glyph/atlas
counts, so a phone's adb logcat can answer the app-switch text loss the
emulator cannot reproduce.

docs/IRIS_TODO.md

@@ -189,8 +189,28 @@ Iris's report on the build with the composing-text, tap-vs-swipe and
 atlas-reset fixes, with a screenshot, verbatim. Each is open until an
 agent ticks it here with the evidence.
 
-- [ ] **"The app definitely does not start with keyboard spacing
+- [x] **"The app definitely does not start with keyboard spacing
   correct. This is how it looks without me doing anything initially."**
+  **Not an inset bug at all -- fixed 2026-09-06.** The black third is the
+  bench shell's own empty *benchmark report* pane: `bench_client.rs`'s
+  root tree gave it `.height(rest(1))` beside `content.height(rest(2))`,
+  so an empty `TextEdit` reserved a third of the window at every launch
+  and pushed the composer up by exactly that. Measured on this checkout's
+  emulator at the phone's own size (1080x2424, density 420, gesture nav),
+  which reproduced Iris's screenshot exactly: new `iris insets:` log line
+  reported `bottom=63 ime_bottom=0` at launch (a nav bar, no keyboard --
+  so the inset the composer was fed was never large), while `ui-trace
+  show -m Message --field box` put the field at `31,1488..1048,1540` on a
+  2282px-tall surface, 789px clear of the bottom -- that pane's third.
+  **Unit mixing checked explicitly and cleared**: `set_bottom_inset` takes
+  physical px and stores `Len::abs`, `MainActivity.java`'s `1`/`0`
+  `ime_bottom` only ever reaches `insets.bottom.max(ime_bottom)` and
+  `> 0.0`, and every `dp` in the composer resolves at layout time. Fix:
+  the report pane is sized to its content (`.max_height(dp(260))
+  .scrollable()`), and moved above the transcript so it cannot eat the
+  composer's nav-bar clearance. After: field box `31,2277..1048,2329`,
+  grey bar ending at device y2361 with the 63px nav strip below it
+  (`/tmp/fix1.png` this pass).
   The screenshot shows the composer bar (the grey band) sitting about
   two thirds of the way down a 704x1568 screen, with black below it to
   the bottom, and the transcript ending at "Claude / Results" just above