feat(mobile): collapsed pill composer and mobile input redesign

Mobile composer redesign: when the keyboard is closed the input collapses
into a narrow pill (sessions, attach, placeholder, mic) with a round
new-session button that fades away on the draft screen. Model and agent
selectors move into a row above the textarea; the draft project/branch
pickers and the attachment menu become searchable bottom sheets reusing
MobileOverlayPanel; a drag handle (also available while dictating) swipes
the composer into and out of a fullscreen mode.

Keyboard-lifecycle hardening: composer controls (agent cycle, dictation
and its overlay controls) no longer steal focus and dismiss the keyboard;
overlays reopen the keyboard on close via a debounced restore chain that
survives menu-to-picker handoffs and skips the native file picker; open
overlays and dictation keep the composer expanded. Dictation starts
directly from the pill and its overlay content fades in after the shape
settles. The keyboard slide compensates the pill-to-full height change in
one motion, and the mobile highlight mirror is disabled so the caret
always matches the text layout.

packages/ui/src/lib/i18n/messages/es.ts

@@ -1886,6 +1886,9 @@ export const dict: Record<I18nKey, string> = {
   "chat.chatInput.previewContextRemove": "Quitar contexto de vista previa",
   "chat.chatInput.projectRoot": "Raíz del proyecto",
   "chat.chatInput.branch": "Rama",
+  "chat.chatInput.draftPicker.projectTitle": "Proyecto",
+  "chat.chatInput.draftPicker.searchProjects": "Buscar proyectos...",
+  "chat.chatInput.draftPicker.searchBranches": "Buscar ramas...",
   "chat.chatInput.worktrees": "Worktrees",
   "chat.chatInput.worktreeNew": "+ Nuevo",
   "chat.chatInput.drop.insertMention": "Suelta para insertar como mención",