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.

internal/config/config.go

@@ -49,6 +49,16 @@ type Server struct {
 	BaseURL          string `yaml:"base_url"`
 	PathPrefix       string `yaml:"path_prefix"`
 	AuthorizationEnv string `yaml:"authorization_env"`
+	// Mihomo external-controller (optional): REST + WebSocket at controller root.
+	MihomoBaseURL           string `yaml:"mihomo_base_url"`
+	MihomoBaseURLEnv        string `yaml:"mihomo_base_url_env"`
+	MihomoAuthorizationEnv  string `yaml:"mihomo_authorization_env"`
+}
+
+// Mihomo holds resolved external-controller upstream for a server alias.
+type Mihomo struct {
+	Base *url.URL
+	Auth string // full Authorization header value (e.g. Bearer <secret>)
 }
 
 // Load reads and validates configuration from path.
@@ -79,6 +89,9 @@ func (c *Config) Validate() error {
 		s.BaseURL = strings.TrimSpace(s.BaseURL)
 		s.PathPrefix = strings.TrimSpace(s.PathPrefix)
 		s.AuthorizationEnv = strings.TrimSpace(s.AuthorizationEnv)
+		s.MihomoBaseURL = strings.TrimSpace(s.MihomoBaseURL)
+		s.MihomoBaseURLEnv = strings.TrimSpace(s.MihomoBaseURLEnv)
+		s.MihomoAuthorizationEnv = strings.TrimSpace(s.MihomoAuthorizationEnv)
 		if s.Alias == "" {
 			return fmt.Errorf("servers[%d]: alias is required", i)
 		}
@@ -106,6 +119,19 @@ func (c *Config) Validate() error {
 		if !strings.HasPrefix(s.PathPrefix, "/") {
 			s.PathPrefix = "/" + s.PathPrefix
 		}
+		hasMihomoURL := s.MihomoBaseURL != "" || s.MihomoBaseURLEnv != ""
+		if hasMihomoURL && s.MihomoAuthorizationEnv == "" {
+			return fmt.Errorf("servers[%d]: mihomo_authorization_env is required when mihomo url is set", i)
+		}
+		if !hasMihomoURL && s.MihomoAuthorizationEnv != "" {
+			return fmt.Errorf("servers[%d]: mihomo_base_url or mihomo_base_url_env is required when mihomo_authorization_env is set", i)
+		}
+		if s.MihomoBaseURL != "" {
+			mu, err := url.Parse(s.MihomoBaseURL)
+			if err != nil || mu.Scheme == "" || mu.Host == "" {
+				return fmt.Errorf("servers[%d]: invalid mihomo_base_url %q", i, s.MihomoBaseURL)
+			}
+		}
 	}
 	if len(c.Servers) == 0 {
 		return fmt.Errorf("at least one server entry is required")
@@ -160,6 +186,7 @@ type Parsed struct {
 	Trusted          []netip.Prefix
 	ByAlias          map[string]*Server
 	AuthByAlias      map[string]string // non-empty Authorization value per alias
+	MihomoByAlias    map[string]*Mihomo
 }
 
 // Parse compiles CIDRs and resolves authorization from environment.
@@ -182,6 +209,7 @@ func (c *Config) Parse() (*Parsed, error) {
 	}
 	by := make(map[string]*Server, len(c.Servers))
 	auth := make(map[string]string)
+	mihomo := make(map[string]*Mihomo)
 	for i := range c.Servers {
 		s := &c.Servers[i]
 		by[s.Alias] = s
@@ -192,12 +220,53 @@ func (c *Config) Parse() (*Parsed, error) {
 			}
 			auth[s.Alias] = v
 		}
+		mu, err := resolveMihomo(s)
+		if err != nil {
+			return nil, err
+		}
+		if mu != nil {
+			mihomo[s.Alias] = mu
+		}
 	}
 	return &Parsed{
-		Config:      c,
-		Whitelist:   wl,
-		Trusted:     tr,
-		ByAlias:     by,
-		AuthByAlias: auth,
+		Config:        c,
+		Whitelist:     wl,
+		Trusted:       tr,
+		ByAlias:       by,
+		AuthByAlias:   auth,
+		MihomoByAlias: mihomo,
 	}, nil
 }
+
+// resolveMihomo returns non-nil only when Mihomo is configured for this server.
+func resolveMihomo(s *Server) (*Mihomo, error) {
+	hasURL := s.MihomoBaseURL != "" || s.MihomoBaseURLEnv != ""
+	if !hasURL {
+		return nil, nil
+	}
+	if s.MihomoAuthorizationEnv == "" {
+		return nil, fmt.Errorf("server %q: mihomo_authorization_env is required when mihomo url is set", s.Alias)
+	}
+	var urlStr string
+	if s.MihomoBaseURLEnv != "" {
+		v := strings.TrimSpace(os.Getenv(s.MihomoBaseURLEnv))
+		if v != "" {
+			urlStr = v
+		}
+	}
+	if urlStr == "" && s.MihomoBaseURL != "" {
+		urlStr = s.MihomoBaseURL
+	}
+	if urlStr == "" {
+		return nil, fmt.Errorf("server %q: mihomo controller url is empty (set mihomo_base_url or env %q)", s.Alias, s.MihomoBaseURLEnv)
+	}
+	u, err := url.Parse(urlStr)
+	if err != nil || u.Scheme == "" || u.Host == "" {
+		return nil, fmt.Errorf("server %q: invalid mihomo controller url %q", s.Alias, urlStr)
+	}
+	authVal := os.Getenv(s.MihomoAuthorizationEnv)
+	if strings.TrimSpace(authVal) == "" {
+		return nil, fmt.Errorf("server %q: env %q is empty or unset", s.Alias, s.MihomoAuthorizationEnv)
+	}
+	return &Mihomo{Base: u, Auth: authVal}, nil
+}