feat: workspaces own their sessions; desktop parity; sidebar and settings cleanup

Workspace sessions (docs/plans/desktop-parity, phases 1-5 and 7):
- sessions.lane_id: a workspace lists only the sessions its panes held,
  stamped by bindRunSession (first writer wins, nested `claude -p`
  excluded); GET /api/sessions?lane=&archived=
- session row state dot, double-click rename, archive (sessions.archived_at,
  hides only); the activity bar's duplicate Sessions tab removed
- Fork beside Resume (--fork-session, Claude only), Ctrl/Cmd+click a live
  session opens it in a second pane, a diff line's comment is pasted into
  the workspace's last-focused pane (lib/panePaste.ts)

dashboard_runs stability:
- a pane's previous run is archived as <pane>@<started_at> instead of being
  overwritten by INSERT OR REPLACE
- a run is flagged abandoned only once its tmux session is gone, at boot and
  on the run-heal beat (panes outlive a server restart)

UI:
- sidebar: no footer, language or theme block; small collapse button in the
  brand corner; version + update check in the connection details modal, a
  status-bar dot while a release is out; language in Settings -> General
- one Switch component for every switch, the themed Checkbox for every
  checkbox (no native checkboxes)

Also: AI Tools catalog trimmed to 10 built-ins (custom-file prompt modes
tested through fixtures), and the workspace plans under docs/plans/ (the
multi-user server plan lives in the AgentHub-Server repo).

client/src/components/StatusBar.tsx

@@ -1,7 +1,8 @@
 /**
  * @file StatusBar — the one-line bar along the bottom of the app shell, on
  * every page: the live-connection state (click: the connection details modal,
- * which the sidebar owns), the version, how many workspaces are running and how
+ * which the sidebar owns and which also carries the update check), the version
+ * — with a green dot while a newer release is out —, how many workspaces are running and how
  * many need the user (from the shared lane list, no request of its own), and
  * today's spend — the `daily_costs` bucket for the local date from
  * `GET /api/pricing/cost`, the Dashboard's own cost call, re-read every 30 s
@@ -27,11 +28,14 @@ export function StatusBar({
   wsConnected,
   left,
   onConnectionClick,
+  updateAvailable = false,
 }: {
   wsConnected: boolean;
   /** Sidebar width, so the bar starts where the main column does. */
   left: string;
   onConnectionClick: () => void;
+  /** A newer release is out: a dot beside the version. */
+  updateAvailable?: boolean;
 }) {
   const { t } = useTranslation("nav");
   const { lanes } = useLanes();
@@ -73,6 +77,13 @@ export function StatusBar({
         {wsConnected ? <Wifi className="h-3 w-3" /> : <WifiOff className="h-3 w-3" />}
         {wsConnected ? t("live") : t("disconnected")}
         <span className="text-fg-muted">{`v${__APP_VERSION__}`}</span>
+        {updateAvailable && (
+          <span
+            data-testid="status-bar-update"
+            title={t("updateAvailable")}
+            className="h-1.5 w-1.5 rounded-full bg-status-success"
+          />
+        )}
       </button>
       <span data-testid="status-bar-counts">
         {t("statusBar.running", { count: running })}