fix(heal): normalize completed root heal state (#3140)

Clear persisted background heal active state after a deep scanner cycle completes so root heal status does not remain in progress between cycles.

Treat path-based stop for an already missing heal task as stopped while keeping client-token cancellation strict.

Co-authored-by: Henry Guo <marshawcoco@users.noreply.github.com>

crates/heal/src/heal/channel.rs

@@ -281,6 +281,12 @@ impl HealChannelProcessor {
                 data: Some("stopped".as_bytes().to_vec()),
                 error: None,
             },
+            Err(Error::TaskNotFound { .. }) if client_token.is_empty() => HealChannelResponse {
+                request_id,
+                success: true,
+                data: Some("stopped".as_bytes().to_vec()),
+                error: None,
+            },
             Err(err) => HealChannelResponse {
                 request_id,
                 success: false,
@@ -965,6 +971,27 @@ mod tests {
         ));
     }
 
+    #[tokio::test]
+    async fn test_process_cancel_request_treats_unknown_path_as_stopped() {
+        let heal_manager = create_test_heal_manager();
+        let processor = HealChannelProcessor::new(heal_manager);
+        let (tx, rx) = oneshot::channel();
+
+        processor
+            .process_cancel_request(".".to_string(), String::new(), tx)
+            .await
+            .expect("cancel should process");
+
+        let response = rx
+            .await
+            .expect("oneshot should resolve")
+            .expect("cancel response should be returned");
+        assert!(response.success);
+        assert_eq!(response.request_id, ".");
+        assert_eq!(response.data.as_deref(), Some("stopped".as_bytes()));
+        assert!(response.error.is_none());
+    }
+
     #[tokio::test]
     async fn test_process_cancel_request_reports_unknown_task() {
         let heal_manager = create_test_heal_manager();