feat(v1): add local alerts, screenshot and JSONL event log

AlertDispatcher de-duplicates by event_id and fires each side effect once
per CONFIRMED: annotated screenshot, one JSONL line (config_version,
source_id, no rtsp/credentials), sound and popup via injectable sink.
44 tests pass; real-frame artifact smoke verified.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

v1/gui.py

@@ -12,6 +12,7 @@ from typing import Dict, Optional
 import numpy as np
 from PyQt5 import QtCore, QtGui, QtWidgets
 
+from v1.alerts import AlertRecord, AlertSink
 from v1.view_model import (
     FIELD_BOUNDS,
     DraftValidationError,
@@ -69,6 +70,32 @@ def bgr_to_qimage(image: np.ndarray) -> QtGui.QImage:
     ).copy()
 
 
+class QtAlertSink(AlertSink):
+    """Desktop sound + one non-blocking popup per confirmed event (Windows smoke)."""
+
+    def __init__(self, parent: Optional[QtWidgets.QWidget] = None) -> None:
+        self._parent = parent
+
+    def play_sound(self, event) -> None:
+        QtWidgets.QApplication.beep()
+
+    def show_popup(self, record: AlertRecord) -> None:
+        box = QtWidgets.QMessageBox(self._parent)
+        box.setIcon(QtWidgets.QMessageBox.Warning)
+        box.setWindowTitle("确认摔倒")
+        box.setText(
+            "人员 {0} 确认摔倒\n确认延迟 {1:.2f} 秒\n截图：{2}".format(
+                record.event.track_id,
+                record.event.latency_seconds,
+                record.screenshot_path.name,
+            )
+        )
+        box.setStandardButtons(QtWidgets.QMessageBox.Ok)
+        box.button(QtWidgets.QMessageBox.Ok).setText("我已知晓")
+        box.setModal(False)
+        box.show()
+
+
 class VideoView(QtWidgets.QWidget):
     """Paint the latest frame plus box/skeleton/id/state overlays."""