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

gateway/knowledge/README.md

@@ -1,6 +1,6 @@
 # Dexorder Knowledge Base
 
-This directory contains global knowledge documents that are automatically loaded into the RAG system as platform-wide knowledge (user_id="0").
+This directory contains global knowledge documents that are automatically loaded into the agent's context at startup.
 
 ## Structure
 
@@ -40,9 +40,7 @@ Content here...
 
 1. At gateway startup, the DocumentLoader scans this directory
 2. Each markdown file is chunked by headers (max ~1000 tokens per chunk)
-3. Chunks are embedded using the configured embedding service
-4. Embeddings are stored in Qdrant with user_id="0" (global namespace)
-5. Content hash tracking enables incremental updates
+3. Content hash tracking enables incremental updates
 
 ## Updating Documents
 
@@ -55,14 +53,6 @@ Content here...
 - Deploy new version
 - Gateway will detect changes and update vectors automatically
 
-## RAG Integration
-
-When users query the agent:
-1. Their query is embedded
-2. Qdrant searches both global (user_id="0") and user-specific vectors
-3. Relevant chunks from these docs are included in context
-4. LLM generates response with platform knowledge
-
 ## Adding New Documents
 
 1. Create markdown file in appropriate subdirectory
@@ -90,12 +80,3 @@ Check logs for load statistics:
 ```
 Knowledge documents loaded: { loaded: 5, updated: 2, skipped: 3 }
 ```
-
-Monitor Qdrant collection stats:
-```
-GET /health
-{
-  "qdrantVectors": 1234,
-  "qdrantIndexed": 1234
-}
-```