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/pages/SessionsPage.tsx

@@ -52,6 +52,7 @@ export const SessionsPage = () => {
 		handleDelete,
 		handleForceDelete,
 		handleRecreateTunnel,
+		handleRename,
 		clearDirtyDelete,
 	} = useInstanceActions({ onRefresh: loadSessions });
 
@@ -124,6 +125,7 @@ export const SessionsPage = () => {
 								session={lastSession}
 								onOpen={handleOpen}
 								onDelete={handleDelete}
+								onRename={handleRename}
 								isBusy={loadingSessionId === lastSession.id}
 								tunnelHealth={tunnelHealth[lastSession.id] || null}
 							/>
@@ -139,6 +141,7 @@ export const SessionsPage = () => {
 							onStop={handleStop}
 							onDelete={handleDelete}
 							onRecreateTunnel={handleRecreateTunnel}
+							onRename={handleRename}
 							actionBusyId={loadingSessionId}
 							tunnelHealth={tunnelHealth}
 						/>

apps/web/src/pages/WorkspaceDetailPage.tsx

@@ -150,8 +150,16 @@ function MobileTabBar({
 /* ─── Files Tab ─── */
 
 function FilesTab({ workspaceId }: { workspaceId: string }) {
-	const { entries, content, currentPath, loadFile, saveFile, loading, error, navigateTo } =
-		useWorkspaceFiles(workspaceId);
+	const {
+		entries,
+		content,
+		currentPath,
+		loadFile,
+		saveFile,
+		loading,
+		error,
+		navigateTo,
+	} = useWorkspaceFiles(workspaceId);
 	const { status, commit, push, pull, fetch } = useWorkspaceGit(workspaceId);
 	const [selectedPath, setSelectedPath] = useState<string | null>(null);
 	const [editContent, setEditContent] = useState<string | null>(null);