fix(api): delete orphaned sessions when character is deleted

- Add delete_sessions_by_character() method to SessionService that
  cleans up all game sessions associated with a character
- Update delete_character() to hard delete instead of soft delete
- Call session cleanup before deleting character to prevent orphaned data
- Delete associated chat messages when cleaning up sessions
- Update API documentation to reflect new behavior

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

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

api/app/services/character_service.py

@@ -334,7 +334,10 @@ class CharacterService:
 
     def delete_character(self, character_id: str, user_id: str) -> bool:
         """
-        Delete a character (soft delete by marking inactive).
+        Permanently delete a character from the database.
+
+        Also cleans up any game sessions associated with the character
+        to prevent orphaned sessions.
 
         Args:
             character_id: Character ID
@@ -354,11 +357,20 @@ class CharacterService:
             if not character:
                 raise CharacterNotFound(f"Character not found: {character_id}")
 
-            # Soft delete by marking inactive
-            self.db.update_document(
+            # Clean up associated sessions before deleting the character
+            # Local import to avoid circular dependency (session_service imports character_service)
+            from app.services.session_service import get_session_service
+            session_service = get_session_service()
+            deleted_sessions = session_service.delete_sessions_by_character(character_id)
+            if deleted_sessions > 0:
+                logger.info("Cleaned up sessions for deleted character",
+                           character_id=character_id,
+                           sessions_deleted=deleted_sessions)
+
+            # Hard delete - permanently remove from database
+            self.db.delete_document(
                 collection_id=self.collection_id,
-                document_id=character_id,
-                data={'is_active': False}
+                document_id=character_id
             )
 
             logger.info("Character deleted successfully", character_id=character_id)