feat(pages): help-page (support) queue — stream, snapshot, respond, close

Phase 2 of docs/ADMIN_CONTROLS.md: surface the in-game help-page queue to the
website.

- BridgePages.cs: the queue has no EventSink, so it is polled (PageSweepSeconds,
  default 5s) and diffed, keyed by sender serial (one page per player) ->
  page.new / page.updated / page.closed. Inbound pages.snapshot -> pages.list;
  page.respond delivers a staff reply to the player (online: a gump now; offline:
  queued for next login; shows as "Staff") and can close; page.close removes it.
- BridgeConfig/Bridge.cfg: PageSweepSeconds. BridgeBoot: reload re-arms the poll,
  status reports it.
- sidecar/src/web.rs: GET /pages, POST /pages/{id}/respond, POST /pages/{id}/close.
- INTEGRATION.md: page events (§4) and endpoints (§6).
- tools/scaffolding/BridgePageProbe.cs: gated headless verification.

Verified live (probe-seeded tickets): snapshot returns the queue, the poll emits
page.new for both and page.closed on removal, respond -> 200, close removes the
page, unknown page -> 404.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0114TpmrNW4wNXsHq5CR72jQ

overlay/Config/Bridge.cfg

@@ -19,6 +19,11 @@ StatSweepSeconds=30
 DecaySweepSeconds=60
 EconomySweepSeconds=300
 
+# Help-page queue poll. The in-game page queue has no EventSink, so it is diffed on this
+# interval to emit page.new / page.closed / page.updated. A few seconds is fine for a
+# support queue; the full open queue is also available on demand via pages.snapshot.
+PageSweepSeconds=5
+
 # Shown to a player when they run [link. The website page where they enter the code.
 LinkUrl=https://yoursite/link