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/hooks/useSessionStream.ts

@@ -19,8 +19,10 @@ function applyFrame(state: State, frame: WsFrame): State {
       const newMsg: Message = {
         id: frame.message_id,
         session_id: '',
+        chat_id: frame.chat_id ?? '',
         role: frame.role,
         content: '',
+        kind: 'message',
         tool_calls: null,
         tool_results: null,
         status: 'streaming',
@@ -71,8 +73,10 @@ function applyFrame(state: State, frame: WsFrame): State {
       const newMsg: Message = {
         id: frame.tool_message_id,
         session_id: '',
+        chat_id: frame.chat_id ?? '',
         role: 'tool',
         content: '',
+        kind: 'message',
         tool_calls: null,
         tool_results: {
           tool_call_id: frame.tool_call_id,
@@ -115,7 +119,6 @@ function applyFrame(state: State, frame: WsFrame): State {
       };
     }
     case 'session_renamed': {
-      // Side-effect, not state — dispatch via event bus to other hooks.
       sessionEvents.emit({
         type: 'session_renamed',
         session_id: frame.session_id,
@@ -123,6 +126,16 @@ function applyFrame(state: State, frame: WsFrame): State {
       });
       return state;
     }
+    case 'chat_renamed': {
+      sessionEvents.emit({
+        type: 'chat_updated',
+        chat_id: frame.chat_id,
+        session_id: '',
+        name: frame.name,
+        updated_at: new Date().toISOString(),
+      });
+      return state;
+    }
     case 'error': {
       const next = frame.message_id
         ? state.messages.map((m) =>