batch4: chats-in-sessions, force-send, /compact, right-rail file browser

Session 1:N Chat data model with backfill. Workspace switches to client-side
multi-tab pane management. Right-rail file browser with float-over viewer and
click-drag line selection replaces FileBrowserPane. Adds /compact streaming
summarizer (respects compact markers in context builder), force-send (cancels
in-flight, persists partial as 'cancelled', awaits cancellation completion via
deferred Promise + 5s timeout), message queue, stop generation, chat
auto-rename, session archive/unarchive with Closed Sessions section on repo
landing page. CHECK constraints on sessions.status, messages.role,
messages.status with KEEP IN SYNC comments tying to MESSAGE_ROLES /
MESSAGE_STATUSES const arrays. Deletes dead pane routes/hook and the
api.panes.* client block.

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

apps/web/src/App.tsx

@@ -1,11 +1,29 @@
-import { BrowserRouter, Routes, Route } from 'react-router-dom';
+import { useEffect, useState } from 'react';
+import { BrowserRouter, Routes, Route, useParams } from 'react-router-dom';
+import { api } from '@/api/client';
 import { ProjectSidebar } from '@/components/ProjectSidebar';
+import { RightRail } from '@/components/RightRail';
 import { Home } from '@/pages/Home';
 import { Project } from '@/pages/Project';
 import { Session } from '@/pages/Session';
 import { Toaster } from '@/components/ui/sonner';
 import { useUserEvents } from '@/hooks/useUserEvents';
 
+function SessionRightRail() {
+  const { id } = useParams<{ id: string }>();
+  if (!id) return null;
+  return <RightRailForSession sessionId={id} />;
+}
+
+function RightRailForSession({ sessionId }: { sessionId: string }) {
+  const [projectId, setProjectId] = useState<string | null>(null);
+  useEffect(() => {
+    api.sessions.get(sessionId).then((s) => setProjectId(s.project_id)).catch(() => {});
+  }, [sessionId]);
+  if (!projectId) return null;
+  return <RightRail projectId={projectId} />;
+}
+
 function AppShell() {
   useUserEvents();
   return (
@@ -18,6 +36,9 @@ function AppShell() {
           <Route path="/session/:id" element={<Session />} />
         </Routes>
       </main>
+      <Routes>
+        <Route path="/session/:id" element={<SessionRightRail />} />
+      </Routes>
       <Toaster position="bottom-right" />
     </div>
   );