feat: 完善分割工作区导入导出与管理流程

- 新增基于 JWT 当前用户的登录恢复、角色权限、用户管理、审计日志和演示出厂重置后台接口与前端管理页。

- 重串 GT_label 导出和 GT Mask 导入逻辑：导出保留类别真实 maskid，导入仅接受灰度或 RGB 等通道 maskid 图，支持未知 maskid 策略、尺寸最近邻拉伸和导入预览。

- 统一分割结果导出体验：默认当前帧，按项目抽帧顺序和 XhXXmXXsXXXms 时间戳命名 ZIP 与图片，补齐 GT/Pro/Mix/分开 Mask 输出和映射 JSON。

- 调整工作区左侧工具栏：移除创建点/线段入口，新增画笔、橡皮擦及尺寸控制，并按绘制、布尔、导入/AI 工具分组分隔。

- 扩展 Canvas 编辑能力：画笔按语义分类绘制并可自动并入连通选中 mask，橡皮擦对选中区域扣除，优化布尔操作、选区、撤销重做和保存状态联动。

- 优化自动传播时间轴显示：同一蓝色系按传播新旧递进变暗，老传播记录达到阈值后统一旧记录色，并维护范围选择与清空后的历史显示。

- 将 AI 智能分割入口替换为更明确的 AI 元素图标，并同步侧栏、工作区和 AI 页面入口表现。

- 完善模板分类、maskid 工具函数、分类树联动、遮罩透明度、边缘平滑和传播链同步相关前端状态。

- 扩展后端项目、媒体、任务、Dashboard、模板和传播 runner 的用户隔离、任务控制、进度事件与兼容处理。

- 补充前后端测试，覆盖用户管理、GT_label 往返导入导出、GT Mask 校验和预览、画笔/橡皮擦、时间轴传播历史、导出范围、WebSocket 与 API 封装。

- 更新 AGENTS、README 和 doc 文档，记录当前接口契约、实现状态、测试计划、安装说明和 maskid/GT_label 规则。

backend/routers/media.py

@@ -9,8 +9,9 @@ from sqlalchemy.orm import Session
 
 from database import get_db
 from minio_client import upload_file, get_presigned_url
-from models import ProcessingTask, Project
+from models import ProcessingTask, Project, User
 from progress_events import publish_task_progress_event
+from routers.auth import require_editor
 from schemas import ProcessingTaskOut
 from statuses import PROJECT_STATUS_PARSING, PROJECT_STATUS_PENDING, TASK_STATUS_QUEUED
 from worker_tasks import parse_project_media
@@ -34,6 +35,7 @@ async def upload_media(
     file: UploadFile = File(...),
     project_id: Optional[int] = Form(None),
     db: Session = Depends(get_db),
+    current_user: User = Depends(require_editor),
 ) -> dict:
     """Accept a video, image, or DICOM file and store it in MinIO.
 
@@ -62,13 +64,15 @@ async def upload_media(
     file_url = get_presigned_url(object_name, expires=3600)
 
     if project_id:
-        project = db.query(Project).filter(Project.id == project_id).first()
-        if project:
-            project.video_path = object_name
-            db.commit()
-            logger.info("Linked upload to project_id=%s", project_id)
-        else:
-            logger.warning("Project id=%s not found for upload linkage", project_id)
+        project = db.query(Project).filter(
+            Project.id == project_id,
+            Project.owner_user_id == current_user.id,
+        ).first()
+        if not project:
+            raise HTTPException(status_code=404, detail="Project not found")
+        project.video_path = object_name
+        db.commit()
+        logger.info("Linked upload to project_id=%s", project_id)
     else:
         # Auto-create a project named after the file
         project = Project(
@@ -77,6 +81,7 @@ async def upload_media(
             status=PROJECT_STATUS_PENDING,
             video_path=object_name,
             source_type="video",
+            owner_user_id=current_user.id,
         )
         db.add(project)
         db.commit()
@@ -109,6 +114,7 @@ async def upload_dicom_batch(
     files: List[UploadFile] = File(...),
     project_id: Optional[int] = Form(None),
     db: Session = Depends(get_db),
+    current_user: User = Depends(require_editor),
 ) -> dict:
     """Upload multiple .dcm files for a DICOM series.
 
@@ -121,7 +127,10 @@ async def upload_dicom_batch(
     uploaded = []
 
     if project_id:
-        project = db.query(Project).filter(Project.id == project_id).first()
+        project = db.query(Project).filter(
+            Project.id == project_id,
+            Project.owner_user_id == current_user.id,
+        ).first()
         if not project:
             raise HTTPException(status_code=404, detail="Project not found")
     else:
@@ -132,6 +141,7 @@ async def upload_dicom_batch(
             description=f"DICOM series with {len(files)} files",
             status=PROJECT_STATUS_PENDING,
             source_type="dicom",
+            owner_user_id=current_user.id,
         )
         db.add(project)
         db.commit()
@@ -173,13 +183,17 @@ def parse_media(
     max_frames: Optional[int] = Query(None, gt=0),
     target_width: int = Query(640, ge=64, le=4096),
     db: Session = Depends(get_db),
+    current_user: User = Depends(require_editor),
 ) -> ProcessingTask:
     """Create a background task for media frame extraction.
 
     The Celery worker performs the heavy FFmpeg/OpenCV/pydicom work and
     updates the persisted task record as it progresses.
     """
-    project = db.query(Project).filter(Project.id == project_id).first()
+    project = db.query(Project).filter(
+        Project.id == project_id,
+        Project.owner_user_id == current_user.id,
+    ).first()
     if not project:
         raise HTTPException(status_code=404, detail="Project not found")