feat: add multi-session desktop workspace

TEST_PLAN.md

@@ -46,28 +46,14 @@ Prove that the always-running Pi bridge is correctly scoped, recoverable, and us
 
 ## Manual Noctalia checklist
 
-### Startup and routing
+### Aggregate launcher
 
-- [ ] Starting the bridge creates the home agent and shows it in the bar/popover.
-- [ ] Shortcut on a known focused worktree opens that worktree’s agent.
-- [ ] Missing or ambiguous focus opens the selector with home preselected.
-- [ ] Popover project/session manager switches agents explicitly and visibly.
-- [ ] Escape closes the popover without aborting streaming work.
-
-### Status and conversation
-
-- [ ] Bar shows state glyph/color, active project, and attention badge.
-- [ ] Popover streams assistant text and tool activity without blocking the composer.
-- [ ] Prompt, steer, follow-up, and abort map to the intended Pi action.
-- [ ] Queue changes are visible and do not reorder or lose user messages.
-- [ ] Pi model/thinking values display correctly and forwarded changes round-trip from Pi.
-
-### Extension prompts
-
-- [ ] Select, confirm, input, and editor requests render as native popover UI.
-- [ ] The response reaches the originating extension unchanged.
-- [ ] A pending request produces an attention badge while the popover is closed.
-- [ ] TUI-only unsupported custom UI is presented as an explicit unsupported/error state, never silently approved.
+- [ ] The widget shows aggregate open, working, attention, recovering, and error counts from `get_workspace_summary`.
+- [ ] A background session requiring extension attention increases the aggregate attention count.
+- [ ] Clicking the widget starts the bridge when needed and toggles the desktop UI.
+- [ ] Noctalia contains no composer, session switcher, or extension-response control.
+- [ ] The configured `PI_STATUS_UI_BINARY` and fallback binary both launch with `--toggle`.
+- [ ] Restarting Noctalia reconnects to the bridge summary without changing active session runtimes.
 
 ## Soak and fault scenarios