Implement Mihomo external-controller support in configuration and gateway

- Added optional Mihomo configuration fields in `config.compose.yaml` and `config.example.yaml` for enhanced integration with the Mihomo external-controller.
- Updated the `Gateway` to handle Mihomo API requests, including proxying and error handling for Mihomo-specific endpoints.
- Enhanced the documentation in `GATEWAY_RUN.md` to guide users on configuring Mihomo integration.
- Introduced new utility functions in the web client for interacting with Mihomo API endpoints, improving the overall user experience.
- Updated the sidebar in the Svelte components to include a link to the Mihomo section, enhancing navigation.

docker-compose.yml

@@ -8,6 +8,15 @@ services:
       - ./config.compose.yaml:/etc/telemt-gateway/config.yaml:ro
     environment:
       CONFIG_PATH: /etc/telemt-gateway/config.yaml
+      # Опционально: Mihomo в той же Docker-сети, что и gateway (см. docs/GATEWAY_RUN.md)
+      # MIHOMO_CONTROLLER_URL: http://mihomo:9090
+      # TELEMT_MIHOMO_AUTH: Bearer ${CLASH_SECRET}
     # Доступ к Telemt на хосте Linux (host.docker.internal в config.compose.yaml):
     extra_hosts:
       - "host.docker.internal:host-gateway"
+    # При необходимости подключите к сети с контейнером Mihomo:
+    # networks:
+    #   - proxy-net
+# networks:
+#   proxy-net:
+#     external: true