fix: add missing branching files and TypeScript fix

- Add BranchRevivalCard, BranchTransitionBar, useHandoff, useResolutionOutputs, SessionQueuePage
- Fix useFlowPilotSession: add is_branching/active_branch_id defaults

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/pages/SessionQueuePage.tsx

@@ -0,0 +1,54 @@
+import { useEffect } from 'react'
+import { useNavigate } from 'react-router-dom'
+import { Inbox, ArrowUpRight, Pause, Clock } from 'lucide-react'
+import { useHandoff } from '@/hooks/useHandoff'
+
+export default function SessionQueuePage() {
+  const navigate = useNavigate()
+  const { queue, isLoadingQueue, loadQueue, claimHandoff } = useHandoff()
+
+  useEffect(() => { loadQueue() }, [loadQueue])
+
+  const handleClaim = async (item: typeof queue[0]) => {
+    const result = await claimHandoff(item.session_id, item.handoff_id)
+    if (result) navigate(`/pilot?sessionId=${item.session_id}`)
+  }
+
+  return (
+    <div className="flex-1 p-6">
+      <div className="flex items-center gap-2 mb-6">
+        <Inbox size={20} className="text-accent" />
+        <h1 className="text-xl font-heading font-bold text-heading">Session Queue</h1>
+      </div>
+      {isLoadingQueue ? (
+        <p className="text-sm text-muted">Loading queue...</p>
+      ) : queue.length === 0 ? (
+        <div className="text-center py-12">
+          <Inbox size={40} className="text-muted mx-auto mb-3" />
+          <p className="text-sm text-muted">No sessions waiting</p>
+        </div>
+      ) : (
+        <div className="space-y-2">
+          {queue.map(item => (
+            <div key={item.handoff_id} className="bg-card border border-default rounded-lg p-4 flex items-center justify-between hover:border-hover transition-colors">
+              <div className="flex-1">
+                <div className="flex items-center gap-2 mb-1">
+                  {item.intent === 'escalate' ? <ArrowUpRight size={14} className="text-red-400" /> : <Pause size={14} className="text-yellow-400" />}
+                  <span className="text-sm font-medium text-heading">{item.problem_summary || 'Untitled session'}</span>
+                  {item.priority === 'elevated' && <span className="text-[10px] px-1.5 py-0.5 rounded-full bg-red-400/10 text-red-400">Elevated</span>}
+                </div>
+                {item.engineer_notes && <p className="text-xs text-secondary">{item.engineer_notes}</p>}
+                <div className="flex items-center gap-2 mt-1 text-xs text-muted">
+                  <Clock size={10} />
+                  <span>{new Date(item.created_at).toLocaleString()}</span>
+                  {item.problem_domain && <span>· {item.problem_domain}</span>}
+                </div>
+              </div>
+              <button onClick={() => handleClaim(item)} className="px-3 py-1.5 text-xs bg-accent text-white rounded-[5px] hover:bg-accent/90">Claim</button>
+            </div>
+          ))}
+        </div>
+      )}
+    </div>
+  )
+}