Hermes Desktop sends probe requests to validate providers before allowing
model switching. The router was returning 503 for all of these because
the catch-all proxy requires a 'model' field in the request body.
Added explicit handlers for:
- GET /v1/models/{model_id} — OpenAI single-model lookup
- GET /api/tags — Ollama model list discovery
- POST /api/show — Ollama model info
- GET /api/v1/models — Ollama-compatible model list
- GET /v1/props, GET /props — llama.cpp server properties
- GET /version — llama.cpp version
Also fixed the catch-all proxy to route requests with no model body to
the currently active backend instead of returning 503.
2c23faa4a1