feat: query fuzzy search + observability + edge schema fix

- Add fuzzy ILIKE search on entity name/description
- Add observability logging (query_entity_search event)
- Fix edge schema: source_entity_id→source_id, target_entity_id→target_id

crates/mem-cli/src/http_server.rs

@@ -1342,16 +1342,30 @@ async fn query_temporal_graph(
     state: &web::Data<AppState>,
     params: &QueryParams,
 ) -> anyhow::Result<serde_json::Value> {
-    // Step 1: Find entities (order by name for deterministic results)
+    // Step 1: Find entities matching question (fuzzy name/description search)
     let entities_rows: Vec<(String, String, String)> = sqlx::query_as(
-        "SELECT id, name, entity_type FROM memory_entity WHERE project_id = $1 LIMIT $2"
+        "SELECT id, name, entity_type FROM memory_entity 
+         WHERE project_id = $1 
+           AND (name ILIKE '%' || $2 || '%' OR description ILIKE '%' || $2 || '%')
+         ORDER BY confidence DESC
+         LIMIT $3"
     )
     .bind(&params.project)
+    .bind(&params.question)
     .bind(params.limit as i32)
     .fetch_all(&state.pool)
     .await
     .unwrap_or_default();
 
+    tracing::info!(
+        target: "observability",
+        event = "query_entity_search",
+        project = %params.project,
+        question = %params.question,
+        matched = entities_rows.len(),
+        "Entity search complete"
+    );
+    
     // Step 2: Traverse edges from found entities
     // NOTE: Edges will be empty until temporal schema is migrated
     let mut edges_data: Vec<(String, String, String, String, String, f32)> = Vec::new();
@@ -1360,7 +1374,7 @@ async fn query_temporal_graph(
     for (entity_id, _name, _type_str) in &entities_rows {
         let entity_edges: Vec<(String, String, String, String, f32, Option<chrono::DateTime<chrono::Utc>>, Option<chrono::DateTime<chrono::Utc>>)> = 
             sqlx::query_as(
-                "SELECT id, target_entity_id, relation_type, fact, confidence, t_valid, t_invalid FROM memory_edge WHERE project_id = $1 AND source_entity_id = $2"
+                "SELECT id, target_id, relation_type, fact, confidence, t_valid, t_invalid FROM memory_edge WHERE project_id = $1 AND source_id = $2"
             )
             .bind(&params.project)
             .bind(entity_id)