桌面 GUI 外链修复 + 主题顺序调整（含结构扁平化进行中的工作区基线）

- 集成 tauri-plugin-opener：Cargo/lib.rs/capabilities/npm 四处接线，新增 src/openExternal.ts（桌面走 opener，浏览器回退 window.open，相对路径绝对化）
- 关于页 4 个链接、活动栏官网菜单、代理错误横幅 2 处健康检查链接全部改走 openExternal，桌面端可正常跳转
- 设置→外观 主题顺序调整为 深色/浅色/跟随系统
- release 二进制重编并验证（浏览器实测关于页链接可开文档页）
- 附带工作区中未提交的扁平化重构现状（另一会话进行中）
- homepage 落地页与文档终检通过（8787 / 与 /docs 双 200）

server/internal/echo/echo.go

@@ -0,0 +1,154 @@
+// Package echo 提供本地 HTTP 回显，供自动化回归套件使用（不依赖外网 httpbin）。
+package echo
+
+import (
+	"encoding/base64"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+)
+
+// Mount registers /v1/echo/* routes.
+func Mount(r *gin.Engine) {
+	e := r.Group("/v1/echo")
+	e.GET("/get", getEcho)
+	e.POST("/json", jsonEcho)
+	e.POST("/form", formEcho)
+	e.POST("/multipart", multipartEcho)
+	e.GET("/headers", headersEcho)
+	e.GET("/cookies", cookiesEcho)
+	e.GET("/bearer", bearerEcho)
+	e.GET("/basic", basicEcho)
+}
+
+func baseMeta(c *gin.Context) gin.H {
+	hdrs := gin.H{}
+	for k, v := range c.Request.Header {
+		if len(v) == 1 {
+			hdrs[k] = v[0]
+		} else {
+			hdrs[k] = v
+		}
+	}
+	q := gin.H{}
+	for k, v := range c.Request.URL.Query() {
+		if len(v) == 1 {
+			q[k] = v[0]
+		} else {
+			q[k] = v
+		}
+	}
+	return gin.H{
+		"ok":      true,
+		"service": "opsxapi-echo",
+		"method":  c.Request.Method,
+		"path":    c.Request.URL.Path,
+		"query":   q,
+		"headers": hdrs,
+	}
+}
+
+func getEcho(c *gin.Context) {
+	c.JSON(http.StatusOK, baseMeta(c))
+}
+
+func jsonEcho(c *gin.Context) {
+	body, _ := io.ReadAll(c.Request.Body)
+	out := baseMeta(c)
+	out["bodyRaw"] = string(body)
+	c.JSON(http.StatusOK, out)
+}
+
+func formEcho(c *gin.Context) {
+	_ = c.Request.ParseForm()
+	form := gin.H{}
+	for k, v := range c.Request.PostForm {
+		if len(v) == 1 {
+			form[k] = v[0]
+		} else {
+			form[k] = v
+		}
+	}
+	out := baseMeta(c)
+	out["form"] = form
+	c.JSON(http.StatusOK, out)
+}
+
+func multipartEcho(c *gin.Context) {
+	_ = c.Request.ParseMultipartForm(8 << 20)
+	form := gin.H{}
+	if c.Request.MultipartForm != nil {
+		for k, v := range c.Request.MultipartForm.Value {
+			if len(v) == 1 {
+				form[k] = v[0]
+			} else {
+				form[k] = v
+			}
+		}
+	}
+	out := baseMeta(c)
+	out["form"] = form
+	c.JSON(http.StatusOK, out)
+}
+
+func headersEcho(c *gin.Context) {
+	out := baseMeta(c)
+	out["xOpsxProbe"] = c.GetHeader("X-Opsx-Probe")
+	c.JSON(http.StatusOK, out)
+}
+
+func cookiesEcho(c *gin.Context) {
+	out := baseMeta(c)
+	cookies := gin.H{}
+	for _, ck := range c.Request.Cookies() {
+		cookies[ck.Name] = ck.Value
+	}
+	// 浏览器禁止脚本设置 Cookie 头；回归用例改走 X-Opsx-Cookie
+	if raw := c.GetHeader("X-Opsx-Cookie"); raw != "" {
+		for _, part := range strings.Split(raw, ";") {
+			part = strings.TrimSpace(part)
+			if part == "" {
+				continue
+			}
+			kv := strings.SplitN(part, "=", 2)
+			if len(kv) == 2 {
+				cookies[strings.TrimSpace(kv[0])] = strings.TrimSpace(kv[1])
+			}
+		}
+	}
+	out["cookies"] = cookies
+	c.JSON(http.StatusOK, out)
+}
+
+func bearerEcho(c *gin.Context) {
+	auth := c.GetHeader("Authorization")
+	if !strings.HasPrefix(auth, "Bearer ") || strings.TrimSpace(strings.TrimPrefix(auth, "Bearer ")) == "" {
+		c.JSON(http.StatusUnauthorized, gin.H{"ok": false, "error": "missing bearer"})
+		return
+	}
+	out := baseMeta(c)
+	out["authenticated"] = true
+	out["token"] = strings.TrimSpace(strings.TrimPrefix(auth, "Bearer "))
+	c.JSON(http.StatusOK, out)
+}
+
+func basicEcho(c *gin.Context) {
+	auth := c.GetHeader("Authorization")
+	if !strings.HasPrefix(auth, "Basic ") {
+		c.Header("WWW-Authenticate", `Basic realm="opsxapi"`)
+		c.JSON(http.StatusUnauthorized, gin.H{"ok": false, "error": "missing basic"})
+		return
+	}
+	raw, err := base64.StdEncoding.DecodeString(strings.TrimSpace(strings.TrimPrefix(auth, "Basic ")))
+	if err != nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"ok": false, "error": "bad basic"})
+		return
+	}
+	parts := strings.SplitN(string(raw), ":", 2)
+	out := baseMeta(c)
+	out["authenticated"] = true
+	out["user"] = parts[0]
+	c.JSON(http.StatusOK, out)
+}