Add provider-scoped runtime monitor for Codex pool owners:
- New `GET /v1/providers/{id}/codex-pool-activity` endpoint aggregates pool health across all agents
- New Pool Activity section on provider detail page (pool owners only)
- Shows aggregate member health, recent requests, top agents with drill-down links
- 7-day time window on provider-scoped span query for performance
- Reuses `buildCodexPoolActivity()` — zero duplicated aggregation logic
- i18n complete (en/vi/zh), accessible markup
Closes#499
- fix Rules of Hooks violation in chatgpt-oauth-routing-section
- add stale-while-revalidate with atomic dedup for RouteEligibility
- move raw SQL from HTTP handler to TracingStore.ListCodexPoolSpans
- persist round-robin state in Registry shared counter
- extract duplicated frontend helpers to agent-display-utils
- split oversized frontend files (964→214 lines max)
- add GIN indexes for spans.metadata and sessions.metadata
- fix tenant-aware provider lookup in handleQuota
- separate empty-role vs error handling in resolveTenantHint
- scope pool validation to chatgpt_oauth providers only
- wrap buildEntries in useCallback for stable useMemo deps
- document OAuth concurrent auth limitation and RoleAdmin breaking change