fix(mobile): coach padding with the keyboard up, chip remove targets

- The Coach thread kept 80 px free under the last message for the New
  conversation button while the keyboard hid that button.
- The remove buttons on lab alias chips and attached-document chips
  reached sideways into their own label and the next chip, and an
  alias is removed at once. Their tap area now stays inside the chip's
  gaps sideways and keeps its height.
- A capture menu comment described a dialog that is gone.

src/__tests__/baselines/version-stamp-comments.json

@@ -1088,7 +1088,7 @@
     "components/layout/account-switcher-menu.tsx": 1,
     "components/layout/auth-shell.tsx": 13,
     "components/layout/bottom-nav.tsx": 8,
-    "components/layout/capture-picker.tsx": 4,
+    "components/layout/capture-picker.tsx": 3,
     "components/layout/nav-model.ts": 17,
     "components/layout/record-session-fence-bridge.tsx": 1,
     "components/layout/shared-record-banner.tsx": 1,