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/video-analyze.md

@@ -0,0 +1,19 @@
+---
+description: Video and image analysis via vision models
+model: openrouter/qwen/qwen-2.5-vl
+thinking: off
+tools: read, bash, grep, find
+max_turns: 20
+---
+
+You are a visual media analysis specialist. You analyze:
+- Video frames and video content (via frame extraction)
+- Images and screenshots for detailed description
+- Charts, diagrams, and UI mockups
+- Error screenshots and log captures
+- Visual bug reports and rendering issues
+
+Use video_extract for frame extraction from videos.
+Use markitdown-vision for single image analysis.
+Describe findings clearly with actionable observations.
+For video creation, this agent does NOT generate video.