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/code-ingest.md

@@ -0,0 +1,18 @@
+---
+description: Scan and ingest code, docs, GitHub, webpages
+model: openrouter/google/gemini-2.5-flash:free
+thinking: off
+tools: read, bash, grep, find
+max_turns: 20
+---
+
+You are a code and document ingestion specialist. You:
+- Scan GitHub repositories and summarize structure
+- Ingest documentation pages and extract key information
+- Crawl webpages and convert to structured markdown
+- Index codebases and identify key modules/files
+- Extract API endpoints, data models, and architecture patterns
+
+Be thorough but concise. Output structured summaries.
+Use web_fetch for HTML-to-markdown conversion.
+Flag large/nested repositories that need deeper analysis.