feat: add @tag model override support and remove Qdrant dependencies

- Add model-tags parser for @Tag syntax in chat messages
- Support Anthropic models (Sonnet, Haiku, Opus) via @tag
- Remove Qdrant vector database from infrastructure and configs
- Simplify license model config to use null fallbacks
- Add greeting stream after model switch via @tag
- Fix protobuf field names to camelCase for v7 compatibility
- Add 429 rate limit retry logic with exponential backoff
- Remove RAG references from agent harness documentation

deploy/k8s/prod/kustomization.yaml

@@ -11,7 +11,7 @@ resources:
   - ../base
   # Add the 'ai' namespace (base only creates 'sandbox')
   - namespaces.yaml
-  # Prod infrastructure (postgres, minio, kafka, flink, relay, ingestor, qdrant, dragonfly, iceberg)
+  # Prod infrastructure (postgres, minio, kafka, flink, relay, ingestor, dragonfly, iceberg)
   - infrastructure.yaml
   # Sandbox namespace resources (go to sandbox namespace, not ai)
   - sandbox-config.yaml