feat(mobile): v1.8 tab switcher + branch indicator + git_status tool

Mobile header is now two rows. Row 1: hamburger | project · branch
indicator (live via GET /api/projects/:id/git, 30s poll) | ModelPicker |
FolderTree. Row 2: pane-switcher pill (hand-rolled BottomSheet) +
NewPaneMenu. Chat-within-pane navigation hidden on mobile; users switch
panes via the sheet. Cross-tab status sync via chat_status frames
published from inference.ts at working/idle/error transitions; StatusDot
component renders amber-pulse/green/red/gray on each pane row and on
desktop ChatTabBar tabs. Level 1 git awareness exposes a read-only
git_status tool to the model, backed by services/git_meta.ts (execFile
+ 2s timeout + 30s cache). Workspace.tsx now receives panes/chats hooks
as props (hoisted into Session.tsx) so the header pill shares state
with the pane grid.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/src/api/client.ts

@@ -9,6 +9,7 @@ import type {
   ListDirResult,
   ViewFileResult,
   AgentsResponse,
+  GitMeta,
 } from './types';
 
 export class ApiError extends Error {
@@ -87,6 +88,8 @@ export const api = {
       request<ViewFileResult>(`/api/projects/${id}/view_file?path=${encodeURIComponent(path)}`),
     files: (id: string) =>
       request<{ files: string[] }>(`/api/projects/${id}/files`),
+    git: (id: string) =>
+      request<GitMeta>(`/api/projects/${id}/git`),
   },
 
   sessions: {