feat: Add get_proxy_host_logs tool for reading nginx proxy host logs

Reads nginx access/error logs directly from a mounted NPM log directory,
enabling agents to debug proxy issues without SSH access. Requires mounting
NPM's /data/logs volume and setting NPM_LOG_DIR.

Also includes a feature request PRD for proposing a native log API upstream.

src/npm_mcp/config.py

@@ -42,6 +42,9 @@ class Settings(BaseSettings):
     mcp_port: int = 8000
     mcp_transport: str = "stdio"  # "stdio" or "http"
 
+    # Path to NPM log directory (mount NPM's /data/logs here)
+    log_dir: str = ""
+
     # Proxy host creation defaults (JSON string)
     # Example: '{"certificate_id": 24, "ssl_forced": true}'
     proxy_defaults: dict[str, Any] = {}