feat: 历史周报+图片预览+照片管理+导入优化+用户合并

新增:
- 历史周报: Dashboard/周报详情支持周选择器翻看往周，归档只读
- 图片预览: 全屏大图(移动端+PC端)，点击遮罩关闭
- PC端照片管理: 编辑时可上传/删除照片
- 客户导入改为更新模式: 重名自动更新信息，显示操作明细
- 导入跳过原因: 旧周报导入也显示每条跳过原因

优化:
- 填报进度权限: 经理只看到自己，支局长/领导看全员
- 客户经理暖灰色hash标签列
- 用户去重合并(4组)，数据完整迁移
- CLAUDE.md 更新到最新状态

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

backend/app/services/excel_import.py

@@ -15,7 +15,7 @@ from app.models.user import User
 async def import_from_excel(db: AsyncSession, file_bytes: bytes, manager_id: uuid.UUID) -> dict:
     """Parse old weekly report Excel and import data. Returns summary stats."""
     wb = openpyxl.load_workbook(io.BytesIO(file_bytes), data_only=True)
-    stats = {"visits": 0, "work_plans": 0, "mini_business": 0, "key_visits": 0, "skipped": 0}
+    stats = {"visits": 0, "work_plans": 0, "mini_business": 0, "key_visits": 0, "skipped": 0, "skip_reasons": []}
 
     # Resolve customer name -> id cache
     customers_result = await db.execute(select(Customer.id, Customer.name))
@@ -38,6 +38,7 @@ async def import_from_excel(db: AsyncSession, file_bytes: bytes, manager_id: uui
                 customer_id = customer_map.get(cust_name)
                 if not customer_id:
                     stats["skipped"] += 1
+                    stats["skip_reasons"].append(f"客户「{cust_name}」不存在，跳过")
                     continue
 
                 try:
@@ -54,6 +55,7 @@ async def import_from_excel(db: AsyncSession, file_bytes: bytes, manager_id: uui
                 )
                 if existing.scalar_one_or_none():
                     stats["skipped"] += 1
+                    stats["skip_reasons"].append(f"重复：{cust_name} {visit_date} 已存在")
                     continue
 
                 visit = Visit(