fix: add SQLite busy_timeout and detailed error messages

- Set busy_timeout=5000ms to handle concurrent write contention
  instead of failing immediately with SQLITE_BUSY
- Return actual error message in usage report API response
  to help diagnose server-side failures

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jx453331958

src/app/api/usage/report/route.ts

@@ -84,7 +84,8 @@ export async function POST(request: NextRequest) {
       skipped,
     });
   } catch (error) {
-    console.error('Error reporting usage:', error);
-    return NextResponse.json({ error: 'Internal server error' }, { status: 500 });
+    const message = error instanceof Error ? error.message : String(error);
+    console.error('Error reporting usage:', message);
+    return NextResponse.json({ error: `Internal server error: ${message}` }, { status: 500 });
   }
 }

src/lib/db.ts

@@ -21,6 +21,8 @@ function getDatabase(): Database.Database {
 
     // Enable WAL mode for better concurrent access
     db.pragma('journal_mode = WAL');
+    // Wait up to 5 seconds when database is locked instead of failing immediately
+    db.pragma('busy_timeout = 5000');
 
     // Initialize schema on first access
     initializeDatabase();