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/features/session/session-list.tsx

@@ -9,6 +9,7 @@ export interface SessionListProps {
   onStop?: (session: Session) => void;
   onDelete?: (session: Session) => void;
   onRecreateTunnel?: (session: Session) => void;
+  onRename?: (session: Session, newName: string) => void;
   actionBusyId?: string | null;
   tunnelHealth?: Record<string, InstanceHealth>;
   showGrouping?: boolean;
@@ -28,6 +29,7 @@ export function SessionList({
   onStop,
   onDelete,
   onRecreateTunnel,
+  onRename,
   actionBusyId = null,
   tunnelHealth = {},
   showGrouping = true,
@@ -56,6 +58,7 @@ export function SessionList({
               onStop={onStop}
               onDelete={onDelete}
               onRecreateTunnel={onRecreateTunnel}
+              onRename={onRename}
               isBusy={actionBusyId === session.id}
               tunnelHealth={tunnelHealth[session.id] || null}
             />
@@ -88,6 +91,7 @@ export function SessionList({
                 onStop={onStop}
                 onDelete={onDelete}
                 onRecreateTunnel={onRecreateTunnel}
+                onRename={onRename}
                 isBusy={actionBusyId === session.id}
                 tunnelHealth={tunnelHealth[session.id] || null}
               />
@@ -113,6 +117,7 @@ export function SessionList({
                 onStop={onStop}
                 onDelete={onDelete}
                 onRecreateTunnel={onRecreateTunnel}
+                onRename={onRename}
                 isBusy={actionBusyId === session.id}
                 tunnelHealth={tunnelHealth[session.id] || null}
               />