Add management API handlers for config and auth file management

- Implemented CRUD operations for authentication files.
- Added endpoints for managing API keys, quotas, proxy settings, and other configurations.
- Enhanced management access with robust validation, remote access control, and persistence support.
- Updated README with new configuration details.

Fixed OpenAI Chat Completions for codex

config.example.yaml

@@ -1,6 +1,17 @@
 # Server port
 port: 8317
 
+# Management API settings
+remote-management:
+  # Whether to allow remote (non-localhost) management access.
+  # When false, only localhost can access management endpoints (a key is still required).
+  allow-remote: false
+
+  # Management key. If a plaintext value is provided here, it will be hashed on startup.
+  # All management requests (even from localhost) require this key.
+  # Leave empty to disable the Management API entirely (404 for all /v0/management routes).
+  secret-key: ""
+
 # Authentication directory (supports ~ for home directory)
 auth-dir: "~/.cli-proxy-api"
 
@@ -45,4 +56,4 @@ openai-compatibility:
       - "sk-or-v1-...b781"
     models: # The models supported by the provider.
       - name: "moonshotai/kimi-k2:free" # The actual model name.
-        alias: "kimi-k2" # The alias used in the API.
+        alias: "kimi-k2" # The alias used in the API.