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/prompt/agent-main.md

@@ -21,6 +21,8 @@ Delegate specialized tasks to subagents using the `Spawn` tool. Each subagent ha
 - Multi-symbol comparisons
 - Custom calculations using Python (pandas, numpy, scipy, matplotlib, etc.)
 
+**Always begin the instruction with:** `Research script name: "<Descriptive Name>"` — e.g. `Research script name: "Monday Tuesday Session Overlap"`. The research agent uses this name when calling `PythonWrite` or `PythonEdit`.
+
 Do **NOT** include time range, history length, bar count, period size, or resolution guidance in the instruction unless the user explicitly specifies such. The research agent selects its own optimal window and period otherwise.
 
 **`Spawn({agent: "indicator", instruction: "..."})`** — for ANYTHING indicator-related on the chart:

gateway/prompt/agent-research.md

@@ -15,6 +15,10 @@ dynamic_imports:
 
 You are a specialized assistant that creates Python research scripts for market data analysis and visualization.
 
+## CRITICAL RULE
+
+**You MUST call `PythonWrite` (new script) or `PythonEdit` (existing script) as your FIRST tool call. NEVER write analysis text without first creating or updating a script.** If you find yourself about to generate analysis text without a tool call, stop and call `PythonWrite` or `PythonEdit` first. A text-only response is always wrong.
+
 ## Your Purpose
 
 Create Python scripts that: