fix(a11y): Escape no longer yanks focus into the composer (#187 DP9)

RoomView focuses the composer on any "typing" key pressed while nothing
editable has focus, and Escape counted as typing. Closing the GIF picker
with Esc (its focus trap returns focus to the GIF button) therefore
landed in the composer instead, and so did Esc on any other room control.
Escape, CapsLock, Insert, ContextMenu, PrintScreen and Pause are now
excluded like the other non-typing keys.

Verified at 1300 px and 320 px: Esc closes the picker and focus is back
on "Insert GIF"; the 320 px picker fits with no page overflow.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/features/room/RoomView.tsx

@@ -51,7 +51,17 @@ const shouldFocusMessageField = (evt: KeyboardEvent): boolean => {
     code === 'Space' ||
     code === 'Enter' ||
     code === 'NumLock' ||
-    code === 'ScrollLock'
+    code === 'ScrollLock' ||
+    // Not typing: Escape in particular dismisses popouts, and a focus-trap
+    // hands focus back to the opener on Escape. Treating it as "start typing"
+    // yanked focus into the composer instead (#187 DP9: closing the GIF picker
+    // with Esc left focus in the composer, not on the GIF button).
+    code === 'Escape' ||
+    code === 'CapsLock' ||
+    code === 'Insert' ||
+    code === 'ContextMenu' ||
+    code === 'PrintScreen' ||
+    code === 'Pause'
   ) {
     return false;
   }