added basic content_exists method implementation

src/ctp_slack_bot/services/vector_database_service.py

@@ -19,6 +19,28 @@ class VectorDatabaseService(BaseModel): # TODO: this should not rely specificall
         logger.debug("Created {}", self.__class__.__name__)
         return self
 
+    def content_exists(self, text: str) -> bool:
+        """
+        Check if a text content already exists in the database.
+        
+        Args:
+            text: The text content to check for existence
+            
+        Returns:
+            bool: True if the content exists, False otherwise
+        """
+        if not self.mongo_db.initialized:
+            self.mongo_db.initialize()
+            
+        try:
+            # Check if the content already exists
+            result = self.mongo_db.vector_collection.find_one({"text": text})
+            
+            return result is not None   
+        except Exception as e:
+            logger.error(f"Error checking content existence: {str(e)}")
+            raise
+    
     def store(self, text: str, embedding: List[float], metadata: Dict[str, Any]) -> str:
         """
         Store text and its embedding vector in the database.