feat: 管理端板块管理与旧版数据导入，补充部署运营文档

- 新增管理端板块管理页面与后端接口（admin_board）
- 新增旧版数据导入：legacyimport 服务、导入面板、importusers 命令行工具
- 聊天用户卡片、板块图标等 UI 组件与界面优化
- 补充 about/公告/1Panel 部署等文档
- gitignore 排除 dist/ 构建产物与 .agents/ 本地工具目录

backend/go.mod

@@ -18,6 +18,9 @@ require (
 )
 
 require (
+	github.com/JohannesKaufmann/html-to-markdown v1.6.0 // indirect
+	github.com/PuerkitoBio/goquery v1.9.2 // indirect
+	github.com/andybalholm/cascadia v1.3.2 // indirect
 	github.com/bytedance/sonic v1.11.6 // indirect
 	github.com/bytedance/sonic/loader v0.1.1 // indirect
 	github.com/cloudwego/base64x v0.1.4 // indirect
@@ -25,6 +28,8 @@ require (
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.3 // indirect
 	github.com/gin-contrib/sse v0.1.0 // indirect
+	github.com/glebarez/go-sqlite v1.21.2 // indirect
+	github.com/glebarez/sqlite v1.11.0 // indirect
 	github.com/go-ini/ini v1.67.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
@@ -47,6 +52,7 @@ require (
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.2 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/rs/xid v1.6.0 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.12 // indirect
@@ -56,4 +62,8 @@ require (
 	golang.org/x/sys v0.48.0 // indirect
 	google.golang.org/protobuf v1.34.1 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
+	modernc.org/libc v1.22.5 // indirect
+	modernc.org/mathutil v1.5.0 // indirect
+	modernc.org/memory v1.5.0 // indirect
+	modernc.org/sqlite v1.23.1 // indirect
 )