fix: resolve mem-cli build errors

Fix u32 vs i32 type mismatch in agent_handler for PostgreSQL binding
Remove unused imports and variables

crates/mem-ingest/src/entity_extractor.rs

@@ -44,7 +44,7 @@ impl ExtractedEntity {
 #[async_trait]
 pub trait EntityExtractor: Send + Sync {
     async fn extract(&self, text: &str) -> Result<Vec<ExtractedEntity>>;
-    async fn extract_with_auth(&self, text: &str, x_forward_user: Option<&str>) -> Result<Vec<ExtractedEntity>> {
+    async fn extract_with_auth(&self, text: &str, _x_forward_user: Option<&str>) -> Result<Vec<ExtractedEntity>> {
         // Default: ignore auth header, use regular extract
         self.extract(text).await
     }