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/components/ChatTabBar.tsx

@@ -1,6 +1,7 @@
 import { useState } from 'react';
 import { History, MessageSquare, Plus, X } from 'lucide-react';
 import type { Chat, WorkspacePane } from '@/api/types';
+import { StatusDot } from '@/components/StatusDot';
 import {
   ContextMenu,
   ContextMenuContent,
@@ -66,7 +67,7 @@ export function ChatTabBar({
   }
 
   return (
-    <div className="flex items-center border-b border-border bg-muted/20 h-8 shrink-0 overflow-x-auto">
+    <div className="flex items-center border-b border-border bg-muted/20 h-8 shrink-0 overflow-x-auto max-md:hidden">
       {tabs.map((chat, tabIdx) => {
         const isActive = tabIdx === pane.activeChatIdx;
         const isLast = tabIdx === tabs.length - 1;
@@ -91,6 +92,7 @@ export function ChatTabBar({
                 )}
               >
                 <MessageSquare size={12} className="shrink-0" />
+                <StatusDot chatId={chat.id} />
                 {renamingId === chat.id ? (
                   <input
                     autoFocus