feat(school,classes): 实现 P2 长期问题全量改进项

P2-2: 新增 OrgTreeNav 组件（学校→年级→班级三级树形导航，支持搜索过滤/选中高亮/展开折叠）

P2-3: 新增 promoteGradesAction 年级升级功能（中文数字/阿拉伯数字识别，按 order 降序避免冲突）

P2-4: 新增 bulkEnrollStudentsAction（CSV 批量导入学生）+ bulkAssignSubjectTeachersAction（CSV 批量分配教师）

P2-5: 为 department/academicYear/grade 的 9 个 CRUD Action 补充 logAudit 审计日志

同步更新架构图文档 004/005

src/shared/i18n/messages/en/school.json

@@ -122,7 +122,15 @@
     "optional": "Optional",
     "failedCreate": "Failed to create grade",
     "failedUpdate": "Failed to update grade",
-    "failedDelete": "Failed to delete grade"
+    "failedDelete": "Failed to delete grade",
+    "promote": {
+      "title": "Promote Grades",
+      "description": "Promote all grades of the selected school by one level (e.g., Grade 1 → Grade 2). Historical archives are preserved.",
+      "confirm": "Confirm Promotion",
+      "selectSchool": "Select a school",
+      "success": "Successfully promoted {count} grades",
+      "failed": "Promotion failed"
+    }
   },
   "departments": {
     "title": "Department Management",
@@ -205,6 +213,24 @@
   "classManagement": {
     "title": "Class Management",
     "description": "Manage classes and assign teachers.",
+    "bulk": {
+      "importStudents": {
+        "title": "Bulk Import Students",
+        "description": "One email per line, format: name,email or email only",
+        "placeholder": "John,john@example.com\njane@example.com",
+        "submit": "Import",
+        "success": "Imported {imported} students, {failed} failed",
+        "failed": "Bulk import failed"
+      },
+      "assignTeachers": {
+        "title": "Bulk Assign Teachers",
+        "description": "One row per line: class name,subject,teacher email",
+        "placeholder": "Class 1,Math,john@example.com\nClass 2,English,jane@example.com",
+        "submit": "Assign",
+        "success": "Updated {updated} assignments, {failed} failed",
+        "failed": "Bulk assignment failed"
+      }
+    },
     "grade": {
       "title": "Class Management",
       "description": "Manage classes for your grades.",
@@ -253,5 +279,12 @@
       "description": "An error occurred while loading data. Please retry.",
       "retry": "Retry"
     }
+  },
+  "orgTree": {
+    "title": "Organization",
+    "search": "Search school/grade/class...",
+    "empty": "No data",
+    "expandAll": "Expand All",
+    "collapseAll": "Collapse All"
   }
 }