feat: v0.8.x 功能更新与数据维护优化

- MAC地址格式统一为小写 xxxx-xxxx-xxxx，支持三种格式输入
- 更换设备MAC时自动清理OLT新发现列表中的冲突ONU记录
- 设备编辑新增场所类型字段（手动输入），区域改为下拉快速填充
- 编辑/更换设备时自动移除new_devices中同MAC的待入库记录
- 新增登录过期自动跳转（401拦截 + 过期提示）
- 新增关于页面（/about），支持Markdown渲染，管理员可在设置中编辑内容
- 新增device_status_history每日自动清理任务（保留30天）
- 更新README.md和about.md

frontend/package-lock.json

@@ -11,6 +11,7 @@
         "axios": "^1.6.5",
         "echarts": "^5.6.0",
         "element-plus": "^2.5.0",
+        "marked": "^18.0.2",
         "pinia": "^2.1.7",
         "vue": "^3.4.0",
         "vue-router": "^4.2.5"
@@ -1452,6 +1453,18 @@
         "@jridgewell/sourcemap-codec": "^1.5.5"
       }
     },
+    "node_modules/marked": {
+      "version": "18.0.2",
+      "resolved": "https://registry.npmmirror.com/marked/-/marked-18.0.2.tgz",
+      "integrity": "sha512-NsmlUYBS/Zg57rgDWMYdnre6OTj4e+qq/JS2ot3KrYLSoHLw+sDu0Nm1ZGpRgYAq6c+b1ekaY5NzVchMCQnzcg==",
+      "license": "MIT",
+      "bin": {
+        "marked": "bin/marked.js"
+      },
+      "engines": {
+        "node": ">= 20"
+      }
+    },
     "node_modules/math-intrinsics": {
       "version": "1.1.0",
       "resolved": "https://registry.npmmirror.com/math-intrinsics/-/math-intrinsics-1.1.0.tgz",