feat: improve session naming, project display, rename support, tab titles

Backend:
- sessions.py: include workspace_name in session response
- instance_service.py: auto-generate display names as
  'Project / Workspace / Tool #N' instead of 'Workspace / Tool #N'
- instance_service.py: add rename_tool_instance() service function
- tool_instances.py: add PATCH /instances/{id} endpoint for renaming
  display_name

Frontend:
- api/sessions.ts: add workspace_name to Session type, add renameInstance()
- use-instance-actions.ts: add handleRename, set document.title when opening
- session-card.tsx: click-to-edit display_name inline; always show project
  context line (Project / Workspace or Repo / Tool)
- session-list.tsx: pass through onRename prop
- SessionsPage.tsx: wire handleRename to SessionCard and SessionList
- app-shell.tsx: sidebar tooltip includes workspace or repo name
- use-terminal-page.ts: set document.title based on active terminal session

Quality gates: py_compile all backend files pass, tsc --noEmit pass,
npm run build pass, 82/82 tests pass

apps/web/src/api/sessions.ts

@@ -26,6 +26,7 @@ export interface Session {
 	repository_id: string;
 	project_name: string;
 	project_id: string;
+	workspace_name?: string | null;
 	status: string;
 	url: string | null;
 	container_status?: string;
@@ -188,6 +189,19 @@ export async function checkInstanceHealth(
 	return response.data;
 }
 
+export async function renameInstance(
+	projectId: string,
+	repoId: string,
+	instanceId: string,
+	displayName: string,
+): Promise<{ id: string; name: string; display_name: string }> {
+	const response = await apiClient.patch(
+		`/projects/${projectId}/repositories/${repoId}/instances/${instanceId}`,
+		{ display_name: displayName },
+	);
+	return response.data;
+}
+
 export async function recreateInstanceTunnel(
 	projectId: string,
 	repoId: string,