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/router/router.go

@@ -4,16 +4,17 @@ package router
 import (
 	"net/http"
 
+	"github.com/modelcontextprotocol/registry/internal/auth"
 	"github.com/modelcontextprotocol/registry/internal/config"
 	"github.com/modelcontextprotocol/registry/internal/service"
 )
 
 // New creates a new router with all API versions registered
-func New(cfg *config.Config, registry service.RegistryService) *http.ServeMux {
+func New(cfg *config.Config, registry service.RegistryService, authService auth.Service) *http.ServeMux {
 	mux := http.NewServeMux()
 
 	// Register routes for all API versions
-	RegisterV0Routes(mux, cfg, registry)
+	RegisterV0Routes(mux, cfg, registry, authService)
 
 	return mux
 }