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/sessionEvents.ts

@@ -2,7 +2,8 @@
 // across hooks (e.g. AI rename arriving via WS in the session view needs to
 // also refresh the sidebar's session list).
 
-import type { Project, Session } from '@/api/types';
+import type { Chat, Project, Session } from '@/api/types';
+import type { Attachment } from '@/lib/attachments';
 
 export interface SessionRenamedEvent {
   type: 'session_renamed';
@@ -51,6 +52,37 @@ export interface OpenFileInBrowserEvent {
   path: string; // project-relative
 }
 
+export interface AttachChatFileEvent {
+  type: 'attach_chat_file';
+  attachment: Omit<Attachment, 'id'>;
+}
+
+export interface SessionArchivedEvent {
+  type: 'session_archived';
+  session_id: string;
+  project_id: string;
+}
+
+export interface ChatCreatedEvent {
+  type: 'chat_created';
+  chat: Chat;
+  session_id: string;
+}
+
+export interface ChatUpdatedEvent {
+  type: 'chat_updated';
+  chat_id: string;
+  session_id: string;
+  name: string | null;
+  updated_at: string;
+}
+
+export interface ChatClosedEvent {
+  type: 'chat_closed';
+  chat_id: string;
+  session_id: string;
+}
+
 export type SessionEvent =
   | SessionRenamedEvent
   | ProjectCreatedEvent
@@ -59,7 +91,12 @@ export type SessionEvent =
   | SessionDeletedEvent
   | SessionUpdatedEvent
   | SessionLoadedEvent
-  | OpenFileInBrowserEvent;
+  | OpenFileInBrowserEvent
+  | AttachChatFileEvent
+  | SessionArchivedEvent
+  | ChatCreatedEvent
+  | ChatUpdatedEvent
+  | ChatClosedEvent;
 type Listener = (event: SessionEvent) => void;
 
 const listeners = new Set<Listener>();