fix(kanban): await plan updates before resolving merge (fixes #243)

Root cause: updatePlans() was fire-and-forget, causing race condition where
resolve() returned before files were written. UI refresh would then read
old 'human_review' status instead of 'done'.

Fix: Await updatePlans() with try/catch to ensure status persists before
UI refresh. Non-fatal error handling preserves existing behavior.

Fixes #243
Related: #586, #216

apps/frontend/src/main/ipc-handlers/task/worktree-handlers.ts

@@ -1766,8 +1766,15 @@ export function registerWorktreeHandlers(
                 }
               };
 
-              // Run async updates without blocking the response
-              updatePlans().catch(err => debug('Background plan update failed:', err));
+              // IMPORTANT: Wait for plan updates to complete before responding (fixes #243)
+              // Previously this was "fire and forget" which caused a race condition:
+              // resolve() would return before files were written, and UI refresh would read old status
+              try {
+                await updatePlans();
+              } catch (err) {
+                debug('Plan update failed:', err);
+                // Non-fatal: UI will still update, but status may not persist across refresh
+              }
 
               const mainWindow = getMainWindow();
               if (mainWindow) {