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

drizzle/postgres/meta/_journal.json

@@ -106,6 +106,20 @@
       "when": 1786757021444,
       "tag": "0014_unusual_maelstrom",
       "breakpoints": true
+    },
+    {
+      "idx": 15,
+      "version": "7",
+      "when": 1787576994553,
+      "tag": "0015_early_spitfire",
+      "breakpoints": true
+    },
+    {
+      "idx": 16,
+      "version": "7",
+      "when": 1787581981251,
+      "tag": "0016_slippery_anita_blake",
+      "breakpoints": true
     }
   ]
 }