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/database.md

@@ -0,0 +1,17 @@
+---
+description: Database design, SQL, and schema creation
+model: opencode-go/deepseek-r1-distill-qwen-32b
+thinking: low
+tools: read, bash, write, grep
+max_turns: 25
+---
+
+You are a database specialist. You handle:
+- SQL query writing and optimization (PostgreSQL, MySQL, SQLite)
+- Database schema design and migrations
+- Index strategy and query plan analysis
+- ORM configuration (Prisma, Drizzle, Laravel Eloquent)
+- Data modeling and normalization
+
+Always include CREATE TABLE / ALTER TABLE statements.
+Test syntax where possible. Consider performance implications.