fix: handle non-UUID sub claim in auth sync

Authentik JWT sub claim may not be a valid UUID.
Now derives a deterministic UUID from the sub string if parsing fails.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/domains/auth/service.py

@@ -102,7 +102,13 @@ class AuthService:
         Returns:
             Tuple of (User, is_new_user)
         """
-        authentik_id = uuid.UUID(token_info.sub)
+        # Parse authentik_id - may be UUID or other format
+        try:
+            authentik_id = uuid.UUID(token_info.sub)
+        except ValueError:
+            # If sub is not a valid UUID, derive one deterministically
+            logger.warning(f"sub claim is not a UUID: {token_info.sub}, deriving UUID")
+            authentik_id = uuid.uuid5(uuid.NAMESPACE_OID, token_info.sub)
 
         # Try to find existing user
         stmt = (
@@ -144,6 +150,74 @@ class AuthService:
         await self.session.flush()
         return user, is_new
 
+    async def sync_user_from_claims(
+        self,
+        authentik_id: uuid.UUID,
+        email: str,
+        name: str,
+        groups: list[str],
+        avatar_url: Optional[str] = None,
+    ) -> tuple[User, bool]:
+        """
+        Create or update user from forward auth claims (NPM X-authentik-* headers)
+
+        This is similar to sync_user() but works with raw claims instead of
+        TokenInfoSchema. Used for auto-syncing users on first web login via NPM.
+
+        Args:
+            authentik_id: The Authentik user UUID (from X-authentik-uid)
+            email: User email (from X-authentik-email)
+            name: User display name (from X-authentik-name)
+            groups: List of group names (from X-authentik-groups)
+            avatar_url: Optional avatar URL
+
+        Returns:
+            Tuple of (User, is_new_user)
+        """
+        # Try to find existing user
+        stmt = (
+            select(User)
+            .options(selectinload(User.roles), selectinload(User.preferences))
+            .where(User.authentik_id == authentik_id)
+        )
+        result = await self.session.execute(stmt)
+        user = result.scalar_one_or_none()
+
+        is_new = user is None
+
+        if is_new:
+            # Create new user
+            user = User(
+                authentik_id=authentik_id,
+                email=email,
+                name=name or email,
+                avatar_url=avatar_url,
+                last_login=datetime.now(timezone.utc),
+            )
+            self.session.add(user)
+            await self.session.flush()  # Get the user ID
+
+            # Create default preferences
+            preferences = UserPreferences(user_id=user.id)
+            self.session.add(preferences)
+
+            logger.info(f"Created new user from forward auth: {email}")
+        else:
+            # Update existing user
+            user.email = email
+            user.name = name or email
+            if avatar_url:
+                user.avatar_url = avatar_url
+            user.last_login = datetime.now(timezone.utc)
+
+            logger.info(f"Updated existing user from forward auth: {email}")
+
+        # Sync roles from groups
+        await self.sync_roles(user, groups)
+
+        await self.session.flush()
+        return user, is_new
+
     async def sync_roles(self, user: User, group_names: list[str]) -> list[Role]:
         """
         Synchronize user roles from Authentik groups via group_roles mapping