Add neutral administrator lobby configuration

Configure supported rules/modules and AI seats or assign an existing human as host without granting private-seat access. Use genuine unused-lobby checks, existing engine actions, live authorization/version/pause/seat fences and atomic audit receipts. Preserve exact account-bound retries across refresh and confirm completed operations after game start without resetting play.

Verified types, lint, 5260 offline tests, 52 HTTP tests and build. Eleven authenticated HTTP groups and independent privacy/persistence review passed. Browser QA confirmed one AI and audit after a lost response and refresh/retry, persisted rules and AI configuration, and readable 1280/390px layouts. All existing rooms and seats preserved. Actual authenticated production administrator acceptance remains pending authorized QA operator access.

README.md

@@ -44,8 +44,10 @@ session controls and a searchable room directory. **Room controls** lets owners
 and operators pause/resume rooms and lock/unlock new joins. See [room controls](docs/ADMIN_ROOM_CONTROLS.md)
 and [initial owner setup](docs/ADMIN_PANEL.md#initial-owner-and-access-recovery).
 Owners/operators can [create a configured lobby](docs/ADMIN_ROOM_CREATION.md) with
-an explicitly owned new host seat and initial AI players. Neutral lobby management,
-archive/removal, participant support and backup tools are still being built.
+an explicitly owned new host seat and initial AI players.
+[Configure lobby](docs/ADMIN_LOBBY_CONFIGURATION.md) manages supported rules, AI
+seats and host assignment without private seat access. Archive/removal, participant
+support and backup tools are still being built.
 
 ## Saved seats and reconnecting