更新品牌文案与演示项目名称

- 登录页和侧栏统一使用根目录 logo_square.png，并更新登录系统名称与副标题。

- 更新 Dashboard、项目库和工作区时间轴文案，移除底层时序视频图层说明。

- 演示视频项目显示名改为“演视LC视频序列”，启动时兼容迁移旧 Data_MyVideo_1 名称，恢复出厂设置使用新名。

- 调整侧栏用户管理入口为用户图标，底部当前用户入口为退出图标，并让退出提示不接收鼠标事件。

- 补充前端组件测试、后端演示重置测试和文档说明。

backend/main.py

@@ -68,6 +68,7 @@ def _seed_default_project_sync() -> None:
     from services.demo_media import (
         DEMO_DICOM_PROJECT_NAME,
         DEMO_VIDEO_PROJECT_NAME,
+        LEGACY_DEMO_VIDEO_PROJECT_NAMES,
         create_parsed_dicom_demo_project,
         create_unparsed_video_demo_project,
         demo_dicom_files,
@@ -76,6 +77,14 @@ def _seed_default_project_sync() -> None:
     db = SessionLocal()
     try:
         admin = ensure_default_admin(db)
+        legacy_video = (
+            db.query(Project)
+            .filter(Project.name.in_(LEGACY_DEMO_VIDEO_PROJECT_NAMES))
+            .first()
+        )
+        if legacy_video is not None:
+            legacy_video.name = DEMO_VIDEO_PROJECT_NAME
+            db.commit()
         existing_video = db.query(Project).filter(Project.name == DEMO_VIDEO_PROJECT_NAME).first()
         if existing_video is None and os.path.exists(settings.demo_video_path):
             video_project = create_unparsed_video_demo_project(

backend/services/demo_media.py

@@ -17,7 +17,8 @@ from statuses import PROJECT_STATUS_PENDING, PROJECT_STATUS_READY
 
 DEMO_DICOM_PROJECT_NAME = "演示DICOM序列"
 DEMO_DICOM_PARSE_FPS = 30.0
-DEMO_VIDEO_PROJECT_NAME = "Data_MyVideo_1"
+DEMO_VIDEO_PROJECT_NAME = "演视LC视频序列"
+LEGACY_DEMO_VIDEO_PROJECT_NAMES = {"Data_MyVideo_1"}
 
 
 def demo_dicom_files(dicom_dir: str) -> list[Path]:

backend/tests/test_admin.py

@@ -194,7 +194,7 @@ def test_demo_factory_reset_leaves_admin_and_parsed_demo_dicom(client, db_sessio
     assert data["project"]["source_type"] == "dicom"
     assert data["project"]["frame_count"] == 3
     assert data["project"]["video_path"] == f"uploads/{data['project']['id']}/dicom"
-    assert [project["name"] for project in data["projects"]] == ["Data_MyVideo_1", "演示DICOM序列"]
+    assert [project["name"] for project in data["projects"]] == ["演视LC视频序列", "演示DICOM序列"]
     assert data["projects"][0]["status"] == "pending"
     assert data["projects"][0]["source_type"] == "video"
     assert data["projects"][0]["frame_count"] == 0