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/configs/gateway-config.yaml

@@ -21,30 +21,6 @@ data:
       model_provider: deepinfra
       model: zai-org/GLM-5
 
-    # License tier model configuration
-    license_models:
-      # Free tier models
-      free:
-        default: zai-org/GLM-5
-        cost_optimized: zai-org/GLM-5
-        complex: zai-org/GLM-5
-        allowed_models:
-          - zai-org/GLM-5
-
-      # Pro tier models
-      pro:
-        default: zai-org/GLM-5
-        cost_optimized: zai-org/GLM-5
-        complex: zai-org/GLM-5
-        blocked_models:
-          - Qwen/Qwen3-235B-A22B-Instruct-2507
-
-      # Enterprise tier models
-      enterprise:
-        default: zai-org/GLM-5
-        cost_optimized: zai-org/GLM-5
-        complex: Qwen/Qwen3-235B-A22B-Instruct-2507
-
     # Kubernetes configuration
     kubernetes:
       namespace: sandbox
@@ -59,11 +35,6 @@ data:
     redis:
       url: redis://dragonfly:6379
 
-    # Qdrant (for RAG vector search)
-    qdrant:
-      url: http://qdrant:6333
-      collection: gateway_memory
-
     # Agent configuration
     agent:
       # Number of prior conversation turns loaded as LLM context and flushed to Iceberg at session end