Add one-use consent for a named player to start seat AI

Let a human owner authorize another human in the started room to start a fixed difficulty once within 24 hours. The owner retains the seat, cookie, private hand, recovery setup and takeback control. Consent is explicit even while online; neither host status nor inactivity authorizes a takeover. Activation enters the existing paced private-view AI path without strategic changes.

Add additive migration 0006, both exact session fences, owner/delegate-only metadata in the authenticated room snapshot, atomic CAS activation and consumption, expiry and terminal retry receipts. Replacement hides older consent; own AI changes invalidate unused consent. Recovery or handover of either bound seat invalidates the grant. Future-version guards prevent stale computed state from overwriting a racing action. Exact browser retry records retain the original operation/version across refresh and cannot rearm old consent. Shared HTTP continuation preserves coalescing across ordinary and control routes.

Independent review found no material remaining issue. Revoke messaging accurately handles activation winning the race. Browser QA exercised grant/revoke, preserved consent after refresh, reciprocal fixed-profile activation, consumed receipts, keyboard takeback and private ownership. The panel now remains expanded after success and action buttons are at least 44px. Responsive screenshot acceptance remains open because the browser viewport override targeted a failed secondary-origin tab; desktop controls and no-overflow width were verified. The QA room is stopped at a genuine human setup decision with both seats taken back.

Types, lint, all 4906 offline tests, production build and all 45 HTTP tests pass on the stable source fingerprint. Seven new offline cases cover client consent/retry validation and real SQLite privacy, restart, one-use races, future versions, takeback, expiry and both-seat recovery/handover; two new HTTP cases cover authentication, injection, fixed-profile continuation and takeback. The first broad run exposed 68 legacy VM fixtures missing the new production dependency; their mappings were updated and the real shared continuation remains exercised. The historical 0005 migration test verifies backfill before applying 0006 for current code.

All 1174 original rooms, 2456 seats and every prior recovery/entry/handover/migration row remain unchanged. SQLite integrity and foreign keys pass; migration and QA added 88 rooms and 188 seats. No reset, server restart, usage check or automation was performed.

The current Sites integration has no supported durable Cron/DO provisioning path. Document this platform blocker rather than adding an inert scheduled export; unattended resumption and broader network-failure acceptance remain unfinished. Full rules, component, AI strength and publication gates remain closed.

Verified source tree: 2d86fc611e9ef4f5a10db10f96687a31db1ec238908ecf1e9333c50fac9ccaa8

docs/MULTIPLAYER_AUDIT.md

@@ -61,7 +61,7 @@ Normal waiting for a temporarily disconnected player is legitimate; it should no
 
 ## Proposed disconnected-seat contract (historical design)
 
-This broader proposal changes operational control of a seat, not board-game rules. Owner recovery and [voluntary handover](SEAT_HANDOVER.md) now have bounded implementations using exact active-token fencing. The separate generation/delegation schema below is historical design and has not been adopted; unattended or host-driven substitution remains unfinished. The passing test count above predates these additions. Preserve the same player ID, faction, resources, hand, traitors, promises, submitted plans, decision ownership and history throughout every transition. Never restart setup or reveal a sealed plan merely because its controller changes.
+This broader proposal changes operational control of a seat, not board-game rules. Owner recovery and [voluntary handover](SEAT_HANDOVER.md) have bounded implementations using exact active-token fencing. The current [one-use named-player AI permission](SEAT_AI_PERMISSION.md) also uses exact session fences while retaining owner control. The separate generation/ownership schema below remains historical design and has not been adopted; unattended or host-driven substitution remains unfinished. The passing test count above predates these additions. Preserve the same player ID, faction, resources, hand, traitors, promises, submitted plans, decision ownership and history throughout every transition. Never restart setup or reveal a sealed plan merely because its controller changes.
 
 ### Distinguish three cases