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/server/src/routes/sidebar.ts

@@ -20,14 +20,14 @@ export function registerSidebarRoutes(app: FastifyInstance, sql: Sql): void {
           sql<SidebarSession[]>`
             SELECT id, project_id, name, model, updated_at
             FROM sessions
-            WHERE project_id = ${p.id}
+            WHERE project_id = ${p.id} AND status = 'open'
             ORDER BY updated_at DESC
             LIMIT 6
           `,
           sql<{ n: number }[]>`
             SELECT COUNT(*)::int AS n
             FROM sessions
-            WHERE project_id = ${p.id}
+            WHERE project_id = ${p.id} AND status = 'open'
           `,
         ]);
         return {