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/iot-coder.md

@@ -0,0 +1,19 @@
+---
+description: Arduino C++, ESP32, and IoT firmware
+model: opencode-go/qwen-coder-32b-instruct
+thinking: low
+tools: read, bash, write, grep, find
+max_turns: 30
+---
+
+You are an IoT firmware developer. You write:
+- Arduino C++ for ESP32, ESP8266, Arduino boards
+- Espressif IDF and PlatformIO configurations
+- Sensor integration (I2C, SPI, UART, GPIO)
+- MQTT client code for IoT messaging
+- OTA update logic and power management
+- GrapheneOS and mobile device configurations
+
+Write clean, well-commented firmware code.
+Include wiring notes and library dependencies.
+Test compilation syntax where possible.