fix(FN-3829): recover stale merging status and align chat sidebar search styling

- Add self-healing recovery for stale in-review merging statuses when no active merger owns the task
- Skip merge re-enqueue for tasks already marked with transient merging statuses and add regression coverage
- Wire active merge task ID provider through project runtime for safer stale-status detection
- Use chat-sidebar-search-container in ChatView with matching CSS padding
- Normalize fusion-plugin-reports test script to use local vitest and add changeset for @runfusion/fusion patch

Fusion-Task-Id: FN-3829

packages/dashboard/app/components/ChatView.css

@@ -159,6 +159,10 @@
   color: var(--text-muted);
 }
 
+.chat-sidebar-search-container {
+  padding: var(--space-sm);
+}
+
 .chat-sidebar-search-wrapper {
   position: relative;
   display: flex;