feat(auth): Implement GitHub OAuth authentication flow for package publishing

- Added authentication service and GitHub OAuth integration.
- Introduced new authentication methods and structures in the model.
- Updated the API to handle authentication during the publishing process.
- Created handlers for starting and checking the status of the OAuth flow.
- Enhanced the publish handler to validate authentication credentials.
- Updated configuration to include GitHub OAuth settings.
- Added tests for the OAuth flow and publishing with authentication.
- Updated documentation to reflect changes in the API and authentication process.

internal/api/server.go

@@ -6,27 +6,30 @@ import (
 	"net/http"
 
 	"github.com/modelcontextprotocol/registry/internal/api/router"
+	"github.com/modelcontextprotocol/registry/internal/auth"
 	"github.com/modelcontextprotocol/registry/internal/config"
 	"github.com/modelcontextprotocol/registry/internal/service"
 )
 
 // Server represents the HTTP server
 type Server struct {
-	config   *config.Config
-	registry service.RegistryService
-	router   *http.ServeMux
-	server   *http.Server
+	config      *config.Config
+	registry    service.RegistryService
+	authService auth.Service
+	router      *http.ServeMux
+	server      *http.Server
 }
 
 // NewServer creates a new HTTP server
-func NewServer(cfg *config.Config, registryService service.RegistryService) *Server {
+func NewServer(cfg *config.Config, registryService service.RegistryService, authService auth.Service) *Server {
 	// Create router with all API versions registered
-	mux := router.New(cfg, registryService)
+	mux := router.New(cfg, registryService, authService)
 
 	server := &Server{
-		config:   cfg,
-		registry: registryService,
-		router:   mux,
+		config:      cfg,
+		registry:    registryService,
+		authService: authService,
+		router:      mux,
 		server: &http.Server{
 			Addr:    cfg.ServerAddress,
 			Handler: mux,