add 11 new sub-agent types, fix model routing, add models.json

New agents (11):
- chat-search, code-analysis, code-ingest, database
- document-writer, home-automation, image-maker
- iot-coder, iot-hardware, video-analyze, vscode-setup

Fixes:
- Remove broken :deepseek suffix from coder-basic, coder-pro,
  devops-basic, devops-pro (caused silent fallback to parent model)
- Add models.json with openRouterRouting for DeepSeek, Qwen,
  MiniMax, Moonshot AI provider cache targeting

Additions:
- headroom-bridge extension (compress_for_agent tool)
- models.json with provider routing config

Cleanup:
- Remove old pi-subagents extension (replaced by @tintinweb/pi-subagents)

agents/coder-basic.md

@@ -1,6 +1,6 @@
 ---
 description: Code editing (React, PHP, Python, Arduino)
-model: openrouter/deepseek/deepseek-chat:deepseek
+model: openrouter/deepseek/deepseek-chat
 thinking: low
 tools: read, bash, write, grep, find
 max_turns: 30