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/components/app-shell.tsx

@@ -47,13 +47,18 @@ const SessionItem = ({ session }: { session: Session }) => {
 			? `/instances/${session.id}/terminal`
 			: `/projects/${session.project_id}`;
 
+	const tooltipParts = [session.display_name, session.project_name];
+	if (session.workspace_name) tooltipParts.push(session.workspace_name);
+	else if (session.repository_name) tooltipParts.push(session.repository_name);
+	tooltipParts.push(`(${session.status})`);
+
 	return (
 		<a
 			href={href}
 			target={`session-${session.id}`}
 			rel="noreferrer"
 			className="nav-item session-item"
-			title={`${session.display_name} (${session.status})`}
+			title={tooltipParts.join(" ")}
 		>
 			<span className={`session-status ${isRunning ? "running" : ""}`} />
 			<Icon name={session.tool_icon as IconName} size="sm" />