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/useProjects.ts

@@ -1,7 +1,6 @@
 import { useCallback, useEffect, useState } from 'react';
 import { api } from '@/api/client';
 import type { Project } from '@/api/types';
-import { sessionEvents } from './sessionEvents';
 
 export function useProjects() {
   const [projects, setProjects] = useState<Project[] | null>(null);
@@ -33,7 +32,6 @@ export function useProjects() {
   const remove = useCallback(
     async (id: string) => {
       await api.projects.remove(id);
-      sessionEvents.emit({ type: 'project_deleted', project_id: id });
       await refresh();
     },
     [refresh]