feat: Add user profile photo upload with base64 encoding

Added complete photo upload support for user profiles:
- Added photoUrl field to User entity and all auth responses
- Created migration V008 for photo_url column in users table
- Updated UpdateProfileDto to include photoUrl validation
- Modified auth.service.ts to handle photoUrl in all user responses (register, login, getUserById, updateProfile, refreshAccessToken, loginWithExternalAuth)
- Updated AuthResponse interface to include photoUrl
- Updated frontend User and UserProfile interfaces to include photoUrl
- Updated AppShell to display user photoUrl in header avatar
- Fixed ChildDialog to remove invalid props from PhotoUpload component

The photo upload uses base64 encoding (max 5MB) for simplicity and works across all environments. Future enhancement can migrate to CDN/object storage.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

maternal-web/components/layouts/AppShell/AppShell.tsx

@@ -116,6 +116,7 @@ export const AppShell = ({ children }: AppShellProps) => {
             }}
           >
             <Avatar
+              src={user?.photoUrl}
               sx={{
                 width: 36,
                 height: 36,