feat: collaboration rooms with switchable presenter (#1328)

* feat: add collaboration rooms with switchable presenter

Rooms are a group of members watching one stage - the live SSH/RDP/VNC
session the current presenter shares. Any member can take over the
stage; the host can invite, force-stop and end the meeting. Stages
reuse session_shares (new room share type), so gating, recording,
expiry and the global sharing toggle all apply unchanged.

* feat: add stage control handoff to collaboration rooms

The presenter or host can grant any member write access to the live
stage and take it back; members can raise a hand to ask. SSH flips the
participant's permission on the live gate; RDP/VNC re-mint the viewer's
join token. Control clears on every stage switch.

* feat: guest links, role invites and invite awareness for collab rooms

- Anonymous guest link per room (host toggles/rotates), followed by
  polling the public resolve endpoint; SSH guests join over the terminal
  WS with roomGuestToken, guac guests get read-only join tokens
- Invite by role (expands to current members, snapshot semantics)
- Toast when a room you were invited to appears
- Stale stages are cleared lazily when the presenter is gone
- Telnet presenting, expired-tab fallback, documented single-instance
  and guac-kick limits
- Tests for the collab routes, room hub, share access and control flip

* fix: keep remote desktop collaboration read-only

src/ui/shell/tabUtils.tsx

@@ -27,6 +27,7 @@ import {
   Plug,
   ScrollText,
   Sparkles,
+  Presentation,
   Workflow,
 } from "lucide-react";
 import { lazy, Suspense } from "react";
@@ -57,6 +58,11 @@ const loadTerminalFeature = () =>
     default: m.Terminal,
   }));
 const TerminalFeature = lazy(loadTerminalFeature);
+const CollabRoomTab = lazy(() =>
+  import("@/features/collab/CollabRoomTab").then((m) => ({
+    default: m.CollabRoomTab,
+  })),
+);
 const LocalTerminal = lazy(() =>
   import("@/features/local-terminal/LocalTerminal").then((m) => ({
     default: m.LocalTerminal,
@@ -318,6 +324,8 @@ export function tabIcon(type: TabType) {
       return <LayoutGrid className="size-3.5" />;
     case "fleet-inventory":
       return <Boxes className="size-3.5" />;
+    case "collab":
+      return <Presentation className="size-3.5" />;
     case "termix-id":
       return <Fingerprint className="size-3.5" />;
     case "alerts":
@@ -615,6 +623,11 @@ export function renderTabContent(
         <FleetInventoryTab fleetId={tab.fleetId} isVisible={isVisible} />,
       );
 
+    case "collab":
+      return withTabSuspense(
+        <CollabRoomTab roomId={tab.collabRoomId} isVisible={isVisible} />,
+      );
+
     case "termix-id":
       return withTabSuspense(
         <PanelTabFrame>