优化：工具栏高度对齐+面板统一+远程连接架构+自动恢复预览

- 工具栏：面包屑与右侧组件像素级等高(:deep 34px)、合并重复search handler、统一分隔符样式、删除死代码
- 面板对齐：三面板header统一padding/font-size、文件列表分页固定底部(自定义紧凑)、表头默认隐藏、滚动条统一样式
- 预览区：始终显示空白预览面板、重启自动恢复上次打开文件
- 收藏夹：简化计数显示(共N项)
- 远程连接：ConnectionIndicator自适应UI(无远程显示mini云图标)、ConnectionDialog支持编辑配置、transport抽象层(本地Wails/远程HTTP双模式)、agent后端模块

go.mod

@@ -6,10 +6,12 @@ require (
 	github.com/chromedp/cdproto v0.0.0-20250724212937-08a3db8b4327
 	github.com/chromedp/chromedp v0.14.2
 	github.com/glebarez/sqlite v1.11.0
+	github.com/labstack/echo/v4 v4.15.0
 	github.com/shirou/gopsutil/v3 v3.24.5
 	github.com/wailsapp/wails/v2 v2.12.0
 	github.com/yuin/goldmark v1.8.2
 	golang.org/x/sys v0.40.0
+	gopkg.in/yaml.v3 v3.0.1
 	gorm.io/gorm v1.31.1
 )
 
@@ -30,7 +32,6 @@ require (
 	github.com/jchv/go-winloader v0.0.0-20250406163304-c1995be93bd1 // indirect
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
-	github.com/labstack/echo/v4 v4.15.0 // indirect
 	github.com/labstack/gommon v0.4.2 // indirect
 	github.com/leaanthony/go-ansi-parser v1.6.1 // indirect
 	github.com/leaanthony/gosod v1.0.4 // indirect
@@ -59,6 +60,7 @@ require (
 	golang.org/x/exp v0.0.0-20260112195511-716be5621a96 // indirect
 	golang.org/x/net v0.49.0 // indirect
 	golang.org/x/text v0.33.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
 	modernc.org/libc v1.67.7 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.11.0 // indirect