feat: add GUI mvp

src/app/gui/bus_bridge.py

@@ -0,0 +1,40 @@
+from __future__ import annotations
+from typing import Any, Dict
+from PySide6 import QtCore
+
+from ..core.events.event_bus import EventBus
+
+
+class BusBridge(QtCore.QObject):
+    """
+    Bridges backend EventBus async events onto the Qt main thread.
+
+    Emits `event(name, payload)` as a Qt signal, thread-safe.
+    """
+
+    event = QtCore.Signal(str, dict)
+
+    def __init__(self, bus: EventBus, parent: QtCore.QObject | None = None) -> None:
+        super().__init__(parent)
+        self._bus = bus
+
+        for name in (
+            "SyncStarted",
+            "SyncSummary",
+            "SyncFinished",
+            "DownloadStarted",
+            "DownloadProgress",
+            "DownloadCompleted",
+            "DownloadFailed",
+            "RenameApplied",
+            "FileRecycled",
+        ):
+            self._bus.subscribe(name, self._make_handler(name))
+
+    def _make_handler(self, name: str):
+        async def handler(payload: Dict[str, Any]) -> None:
+            # Ensure delivery on the Qt main thread.
+            self.event.emit(name, dict(payload))
+
+        return handler
+