Fix Qt cleanup warning with proper worker lifecycle management

- Keep reference to active worker in dialog instance
- Use deleteLater() for Signals QObject cleanup
- Prevents "shared QObject deleted directly" warning

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/ramble/dialog.py

@@ -197,6 +197,7 @@ class RambleDialog(QDialog):
 
         self.thread_pool = QThreadPool.globalInstance()
         self.result: Optional[RambleResult] = None
+        self._active_worker: Optional[GenWorker] = None  # Keep reference to prevent premature GC
 
         self.field_lock_boxes: Dict[str, QCheckBox] = {}
         self.field_outputs: Dict[str, QTextEdit] = {}
@@ -373,10 +374,10 @@ class RambleDialog(QDialog):
         }
 
         self._set_busy(True, "Generating...")
-        worker = GenWorker(self.provider, payload)
+        self._active_worker = GenWorker(self.provider, payload)
-        worker.signals.finished.connect(self._on_generated)
+        self._active_worker.signals.finished.connect(self._on_generated)
-        worker.signals.error.connect(self._on_gen_error)
+        self._active_worker.signals.error.connect(self._on_gen_error)
-        self.thread_pool.start(worker)
+        self.thread_pool.start(self._active_worker)
 
     def _on_generated(self, data: Dict[str, Any]):
         new_fields: Dict[str, str] = data.get("fields", {})
@@ -431,6 +432,10 @@ class RambleDialog(QDialog):
     def closeEvent(self, event):
         """Wait for background workers to finish before closing."""
         self.thread_pool.waitForDone(1000)  # Wait up to 1 second
+        # Clean up worker reference to prevent Qt warning
+        if self._active_worker is not None:
+            self._active_worker.signals.deleteLater()
+            self._active_worker = None
         super().closeEvent(event)