完善项目导入、模板与分割工作区交互

- 增强 DICOM/视频项目导入与演示数据：DICOM 按文件名自然顺序处理，导入后展示上传与解析任务进度，恢复演示出厂设置保留演示视频和演示 DICOM 项目，并补充 demo media seed 逻辑。

- 完善项目管理：项目支持重命名、删除、复制，删除使用站内确认弹窗，复制支持新项目重置和全内容复制，DICOM 项目不显示生成帧入口。

- 完善 GT Mask 与导出链路：只支持 8-bit maskid 图导入，非法/全背景图明确拒绝，尺寸自动适配，高精度 polygon 回显；统一导出默认当前帧，GT_label 使用 uint8 和真实 maskid，待分类 maskid 0 与背景一致。

- 完善分割工作区交互：新增画笔和橡皮擦并支持尺寸控制，移除创建点/线段入口，工具栏按类别分隔，AI 智能分割使用明确 AI 图标，取消黄色 seed point，清空/删除传播 mask 后同步清理空帧时间轴状态。

- 完善传播与时间轴：自动传播使用 SAM 2.1 权重任务，参考帧无遮罩时提示，传播历史按同一蓝色系递进变暗，删除/清空传播链时保留人工或独立 AI 标注来源。

- 完善模板库：新增头颈部 CT 分割默认模板，所有模板保留 maskid 0 待分类，支持鼠标复制模板、拖拽层级、JSON 批量导入预览、删除 label 和站内删除确认。

- 完善用户与高风险确认：用户改密码、删除用户、恢复演示出厂设置和清空人工/AI 标注帧均改为站内确认交互，避免浏览器原生 prompt/confirm。

- 补充前后端测试与文档：更新项目、模板、GT 导入、导出、传播、DICOM、用户管理等测试，并同步 README、AGENTS 和 doc 下实现/契约/测试计划文档。

backend/tests/test_projects.py

@@ -42,6 +42,9 @@ def test_project_crud_and_frames(client, monkeypatch):
     assert updated.json()["name"] == "Renamed"
     assert updated.json()["status"] == "ready"
 
+    empty_name = client.patch(f"/api/projects/{project_id}", json={"name": "   "})
+    assert empty_name.status_code == 400
+
     deleted = client.delete(f"/api/projects/{project_id}")
     assert deleted.status_code == 204
     assert client.get(f"/api/projects/{project_id}").status_code == 404
@@ -83,10 +86,97 @@ def test_delete_project_cascades_related_records(client, db_session):
     assert db_session.query(ProcessingTask).filter(ProcessingTask.project_id == project_id).count() == 0
 
 
+def test_copy_project_reset_copies_frame_sequence_without_annotations(client, db_session):
+    created = client.post("/api/projects", json={
+        "name": "Reset Source",
+        "description": "desc",
+        "video_path": "uploads/source.mp4",
+        "thumbnail_url": "thumb.jpg",
+        "status": "ready",
+        "parse_fps": 12,
+    })
+    assert created.status_code == 201
+    project_id = created.json()["id"]
+    frame = client.post(f"/api/projects/{project_id}/frames", json={
+        "project_id": project_id,
+        "frame_index": 0,
+        "image_url": "frames/source/frame_000000.jpg",
+        "width": 640,
+        "height": 360,
+        "timestamp_ms": 0,
+        "source_frame_number": 0,
+    })
+    assert frame.status_code == 201
+    annotation = client.post("/api/ai/annotate", json={
+        "project_id": project_id,
+        "frame_id": frame.json()["id"],
+        "mask_data": {"label": "Tumor", "polygons": [[[0.1, 0.1], [0.2, 0.1], [0.2, 0.2]]]},
+    })
+    assert annotation.status_code == 201
+
+    copied = client.post(f"/api/projects/{project_id}/copy", json={"mode": "reset"})
+    assert copied.status_code == 201
+    copied_body = copied.json()
+    assert copied_body["name"] == "Reset Source 副本"
+    assert copied_body["frame_count"] == 1
+    assert copied_body["video_path"] == "uploads/source.mp4"
+    assert copied_body["parse_fps"] == 12
+
+    copied_frames = db_session.query(Frame).filter(Frame.project_id == copied_body["id"]).all()
+    assert len(copied_frames) == 1
+    assert copied_frames[0].image_url == "frames/source/frame_000000.jpg"
+    assert db_session.query(Annotation).filter(Annotation.project_id == copied_body["id"]).count() == 0
+
+
+def test_copy_project_full_copies_annotations_and_mask_metadata(client, db_session):
+    created = client.post("/api/projects", json={
+        "name": "Full Source",
+        "status": "ready",
+    })
+    assert created.status_code == 201
+    project_id = created.json()["id"]
+    frame = client.post(f"/api/projects/{project_id}/frames", json={
+        "project_id": project_id,
+        "frame_index": 0,
+        "image_url": "frames/source/frame_000000.jpg",
+        "width": 640,
+        "height": 360,
+    })
+    assert frame.status_code == 201
+    frame_id = frame.json()["id"]
+    annotation = client.post("/api/ai/annotate", json={
+        "project_id": project_id,
+        "frame_id": frame_id,
+        "mask_data": {"label": "Tumor", "polygons": [[[0.1, 0.1], [0.2, 0.1], [0.2, 0.2]]]},
+        "points": [[0.1, 0.1]],
+        "bbox": [0.1, 0.1, 0.1, 0.1],
+    })
+    assert annotation.status_code == 201
+    annotation_id = annotation.json()["id"]
+    db_session.add(Mask(annotation_id=annotation_id, mask_url="masks/source.png", format="png"))
+    db_session.commit()
+
+    copied = client.post(f"/api/projects/{project_id}/copy", json={"mode": "full"})
+    assert copied.status_code == 201
+    copied_body = copied.json()
+    copied_frames = db_session.query(Frame).filter(Frame.project_id == copied_body["id"]).all()
+    copied_annotations = db_session.query(Annotation).filter(Annotation.project_id == copied_body["id"]).all()
+
+    assert copied_body["name"] == "Full Source 副本"
+    assert len(copied_frames) == 1
+    assert len(copied_annotations) == 1
+    assert copied_annotations[0].id != annotation_id
+    assert copied_annotations[0].frame_id == copied_frames[0].id
+    assert copied_annotations[0].mask_data["label"] == "Tumor"
+    assert copied_annotations[0].bbox == [0.1, 0.1, 0.1, 0.1]
+    assert copied_annotations[0].masks[0].mask_url == "masks/source.png"
+
+
 def test_project_and_frame_404s(client):
     assert client.get("/api/projects/999").status_code == 404
     assert client.patch("/api/projects/999", json={"name": "x"}).status_code == 404
     assert client.delete("/api/projects/999").status_code == 404
+    assert client.post("/api/projects/999/copy", json={"mode": "reset"}).status_code == 404
     assert client.post("/api/projects/999/frames", json={
         "project_id": 999,
         "frame_index": 0,