Enhance user profile management and Gravatar integration

- Added email field to user profile API and frontend components for better user identification.
- Implemented PATCH /map/api/me endpoint to update user email, enhancing user experience.
- Introduced useGravatarUrl composable for generating Gravatar URLs based on user email.
- Updated profile and layout components to display user avatars using Gravatar, improving visual consistency.
- Enhanced development documentation to guide testing of navbar and profile features.

internal/app/app.go

@@ -266,6 +266,7 @@ type User struct {
 	Auths      Auths
 	Tokens     []string
 	OAuthLinks map[string]string `json:"oauth_links,omitempty"`
+	Email      string            `json:"email,omitempty"`
 }
 
 // Page holds page metadata for rendering.