修复演示恢复项目帧数据

- 恢复演示出厂设置后直接解析演视LC视频序列并生成可打开帧序列

- 保持演视DICOM序列按文件名自然顺序恢复并生成帧

- 增加 MinIO 浏览器访问端点配置，修复 Docker 部署中封面和帧图预签名地址使用容器内主机名的问题

- 更新管理员恢复测试覆盖视频和 DICOM 帧数量

- 更新 README 和前后端契约/设计/测试文档中的演示恢复说明

backend/services/demo_media.py

@@ -12,12 +12,20 @@ from sqlalchemy.orm import Session
 
 from minio_client import upload_file
 from models import Frame, Project, User
-from services.frame_parser import natural_filename_key, parse_dicom, upload_frames_to_minio
+from services.frame_parser import (
+    extract_thumbnail,
+    natural_filename_key,
+    parse_dicom,
+    parse_video,
+    upload_frames_to_minio,
+)
 from statuses import PROJECT_STATUS_PENDING, PROJECT_STATUS_READY
 
 DEMO_DICOM_PROJECT_NAME = "演视DICOM序列"
 DEMO_DICOM_PARSE_FPS = 30.0
 DEMO_VIDEO_PROJECT_NAME = "演视LC视频序列"
+DEMO_VIDEO_PARSE_FPS = 30.0
+DEMO_VIDEO_TARGET_WIDTH = 640
 LEGACY_DEMO_VIDEO_PROJECT_NAMES = {"Data_MyVideo_1"}
 LEGACY_DEMO_DICOM_PROJECT_NAMES = {"演示DICOM序列"}
 
@@ -67,6 +75,85 @@ def create_unparsed_video_demo_project(
     return project
 
 
+def create_parsed_video_demo_project(
+    db: Session,
+    *,
+    owner: User,
+    video_path: str,
+    project_name: str = DEMO_VIDEO_PROJECT_NAME,
+) -> Project:
+    """Create the bundled demo video project and register its extracted frame sequence."""
+    source = Path(video_path)
+    if not source.exists() or not source.is_file():
+        raise FileNotFoundError(f"Demo video not found: {video_path}")
+
+    project = Project(
+        name=project_name,
+        description="默认演示视频，已生成帧",
+        status=PROJECT_STATUS_PENDING,
+        source_type="video",
+        parse_fps=DEMO_VIDEO_PARSE_FPS,
+        original_fps=None,
+        owner_user_id=owner.id,
+    )
+    db.add(project)
+    db.flush()
+
+    data = source.read_bytes()
+    object_name = f"uploads/{project.id}/{source.name}"
+    upload_file(object_name, data, content_type="video/mp4", length=len(data))
+    project.video_path = object_name
+
+    tmp_dir = tempfile.mkdtemp(prefix=f"seg_demo_video_{project.id}_")
+    try:
+        output_dir = os.path.join(tmp_dir, "frames")
+        frame_files, original_fps = parse_video(
+            str(source),
+            output_dir,
+            fps=int(DEMO_VIDEO_PARSE_FPS),
+            target_width=DEMO_VIDEO_TARGET_WIDTH,
+        )
+        project.original_fps = original_fps
+        object_names = upload_frames_to_minio(frame_files, project.id)
+
+        for idx, obj_name in enumerate(object_names):
+            image = cv2.imread(frame_files[idx])
+            height, width = image.shape[:2] if image is not None else (None, None)
+            db.add(Frame(
+                project_id=project.id,
+                frame_index=idx,
+                image_url=obj_name,
+                width=width,
+                height=height,
+                timestamp_ms=idx * 1000.0 / DEMO_VIDEO_PARSE_FPS,
+                source_frame_number=idx,
+            ))
+
+        thumbnail_path = os.path.join(tmp_dir, "thumbnail.jpg")
+        try:
+            extract_thumbnail(str(source), thumbnail_path)
+            with open(thumbnail_path, "rb") as thumbnail_file:
+                thumbnail_data = thumbnail_file.read()
+            thumbnail_object = f"projects/{project.id}/thumbnail.jpg"
+            upload_file(
+                thumbnail_object,
+                thumbnail_data,
+                content_type="image/jpeg",
+                length=len(thumbnail_data),
+            )
+            project.thumbnail_url = thumbnail_object
+        except Exception:  # noqa: BLE001
+            if object_names:
+                project.thumbnail_url = object_names[0]
+
+        project.status = PROJECT_STATUS_READY
+        db.commit()
+        db.refresh(project)
+        return project
+    finally:
+        shutil.rmtree(tmp_dir, ignore_errors=True)
+
+
 def create_parsed_dicom_demo_project(
     db: Session,
     *,