feat(timeline): 事件时间轴支持删除视频会话

三端联动实现（fam-ui -> fam-core -> fam-edge），沿用项目里"NAS 转发写请求
到 Oracle"的既有模式（照抄 identity_correct 那套骨架）：

- fam-edge：oracle_db.py 新增 delete_video()（删 events+videos 行 + 磁盘上
  的运动片段文件；不清理 ss_motion_events 源事件，因为素材一旦处理完就不会
  被生产者重新捡起，删片段不会触发重新分割）；api_gateway.py 新增
  POST /api/oracle/video/delete
- fam-core：新增 db_layer.delete_sync_video()（第一个"NAS 直接写自己镜像表"
  的函数——增量同步只做 upsert 感知不到删除，不能像纠错那样靠 trigger_now()
  拉增量顺带清理）+ oracle_sync.push_video_delete() + ui_api.py 新增
  DELETE /api/ui/videos/<id>（先回推 Oracle，成功后才清本地镜像，避免数据
  不一致）
- fam-ui：Timeline.vue 详情卡片加删除按钮（原生 confirm() 二次确认，项目里
  之前没有确认弹窗组件先例）；api.js 新增 deleteVideo()

新增 6 个 delete_video 单元测试；已在 Oracle/NAS 用自造测试数据完整跑通端
到端链路（转发成功、两端记录清理、磁盘文件删除、幂等 404），未触碰任何真
实监控数据。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

fam-edge/tests/test_oracle_db.py

@@ -363,3 +363,64 @@ def test_correct_video_identity_without_prior_mapping_uses_current_name_as_raw_u
     rows = db._conn.execute(
         "SELECT person_list_json FROM events WHERE video_id=?", (vid,)).fetchall()
     assert json.loads(rows[0]["person_list_json"]) == ["爸爸"]
+
+
+def test_delete_video_removes_video_and_events_rows(tmp_path):
+    db = _db(tmp_path)
+    vid = _seed_video_with_events(db)
+
+    local_path = db.delete_video(vid)
+
+    assert local_path == f"/tmp/motion_1_1000.mp4"
+    assert db._conn.execute("SELECT * FROM videos WHERE id=?", (vid,)).fetchone() is None
+    assert db._conn.execute("SELECT * FROM events WHERE video_id=?", (vid,)).fetchall() == []
+
+
+def test_delete_video_removes_disk_file(tmp_path):
+    db = _db(tmp_path)
+    clip_path = tmp_path / "motion_9_2000.mp4"
+    clip_path.write_bytes(b"fake mp4 bytes")
+    vid = db.ensure_video("motion_9_2000.mp4", str(clip_path), event_start_time="2026-08-22 10:00:00")
+    db.mark_video_processed(vid, "摘要", [], [], "gemini")
+
+    db.delete_video(vid)
+
+    assert not clip_path.exists()
+
+
+def test_delete_video_missing_file_on_disk_does_not_raise(tmp_path):
+    """核心诉求: local_path 指向的文件已经不存在（比如手动清理过）时，删除记录
+    本身不能因为 os.remove 报错而失败——文件缺失不是数据库操作的错误。"""
+    db = _db(tmp_path)
+    vid = db.ensure_video("motion_9_2000.mp4", str(tmp_path / "already_gone.mp4"),
+                          event_start_time="2026-08-22 10:00:00")
+    db.mark_video_processed(vid, "摘要", [], [], "gemini")
+
+    local_path = db.delete_video(vid)
+
+    assert local_path == str(tmp_path / "already_gone.mp4")
+    assert db._conn.execute("SELECT * FROM videos WHERE id=?", (vid,)).fetchone() is None
+
+
+def test_delete_video_nonexistent_returns_none(tmp_path):
+    db = _db(tmp_path)
+    assert db.delete_video(99999) is None
+
+
+def test_delete_video_does_not_touch_ss_motion_events(tmp_path):
+    """核心诉求: ss_motion_events 是运动侦测源事件，跟切出来的视频片段生命周期
+    独立，删视频不该连带删掉源事件（否则分割逻辑的幂等判断会被破坏）。"""
+    db = _db(tmp_path)
+    db.record_motion_events([
+        {"event_id": 555, "camera_id": 2, "event_type": 10,
+         "start_time": 1700000000, "duration": 10, "thumbnail_url": ""},
+    ])
+    vid = db.ensure_video("motion_555_1700000000.mp4", "/tmp/motion_555_1700000000.mp4",
+                          event_start_time="2026-08-22 10:00:00", motion_event_id=555)
+    db.mark_video_processed(vid, "摘要", [], [], "gemini")
+
+    db.delete_video(vid)
+
+    assert db.get_video_by_motion_event_id(555) is None
+    row = db._conn.execute("SELECT * FROM ss_motion_events WHERE event_id=?", (555,)).fetchone()
+    assert row is not None