feat: MLOps external services, AI stack planning, admin MLOps hub

Infrastructure:
- Add `mlops` compose profile: MLflow (basic-auth, /mlflow path) + Airflow (LocalExecutor, /airflow path) + airflow-db
- infra/mlflow/basic_auth.ini for MLflow auth config
- Caddy routes /mlflow* and /airflow* inside existing o.alogins.net block (see agap_git)
- Dockerfile.admin: NEXT_PUBLIC_MLFLOW_URL / NEXT_PUBLIC_AIRFLOW_URL build args (default /mlflow, /airflow)

Admin panel:
- /admin/models: replace MLflow iframe with external link cards
- /admin/experiments: replace LinUCB stats with MLOps hub (links to MLflow experiments/models + Airflow DAGs/datasets)
- AdminShell: external nav links for MLflow ↗ and Airflow ↗ under MLOps section

Docs & planning:
- README: new AI stack section (Ollama/LiteLLM/OpenWebUI three-tier, tip generation pipeline, model aliases)
- README: Phase 2 expanded with AI infra issues (#86-#93) and granular pipeline breakdown
- README: Phase 4 expanded with LLM MLOps items (#94-#97)
- CLAUDE.md: AI stack section, updated current phase (M1 shipped / M2 in progress), compose profiles, updated What NOT to do
- docs/architecture/overview.md: AI stack section, updated decision flow diagram for Phase 2 LLM pipeline
- ADR-0006: updated to reflect external services (path-based, not embedded)
- Gitea issues #86-#97 created (M2: AI infra + pipeline; M4: LLM MLOps)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/api/src/events/bus.ts

@@ -22,12 +22,27 @@ export type TipServedEvent = {
 export type TipFeedbackEvent = {
   userId: string;
   tipId: string;
-  action: 'done' | 'dismiss' | 'snooze';
+  action: 'done' | 'dismiss' | 'snooze' | 'helpful' | 'not_helpful';
   reward: number;   // inferred from action + dwellMs (see inferReward in recommender.ts)
   dwellMs: number | null;
   createdAt: string;
 };
 
+export type IntegrationTokenExpiredEvent = {
+  userId: string;
+  provider: string;
+  detectedAt: string;
+};
+
+export type RewardDeliveryFailedEvent = {
+  userId: string;
+  tipId: string;
+  reward: number;
+  attempts: number;
+  error: string;
+  failedAt: string;
+};
+
 export type TaskSyncedEvent = {
   userId: string;
   count: number;
@@ -37,7 +52,9 @@ export type TaskSyncedEvent = {
 type EventMap = {
   'signals.tip.served': TipServedEvent;
   'signals.tip.feedback': TipFeedbackEvent;
+  'signals.tip.reward_failed': RewardDeliveryFailedEvent;
   'signals.task.synced': TaskSyncedEvent;
+  'signals.integration.token_expired': IntegrationTokenExpiredEvent;
 };
 
 export type StoredEvent = {