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）

src/features/testing/regression.ts

@@ -0,0 +1,32 @@
+import { createSeedWorkspace } from "../../core/index";
+import { useWorkspace } from "../../workspaceStore";
+const REGRESSION_CASE_ID = "tc-opsx-http8-regression";
+
+/** 装载 / 刷新本地 Gin echo 八组合回归用例（不整库清空） */
+export function installHttp8Regression(): string {
+  const seed = createSeedWorkspace();
+  const state = useWorkspace.getState();
+  const seedCase = seed.testCases.find((c) => c.id === REGRESSION_CASE_ID) ?? seed.testCases[0]!;
+  const localEnv = seed.environments.find((e) => e.name === "本地") ?? seed.environments[0];
+  const hasCase = state.testCases.some((c) => c.id === REGRESSION_CASE_ID);
+  const hasCollection = state.collections.some((c) => c.name === "示例集合");
+  const localExisting = state.environments.find((e) => e.name === "本地");
+  state.loadWorkspaceData({
+    version: 2,
+    collections: hasCollection
+      ? state.collections.map((c) => (c.name === "示例集合" ? seed.collections[0]! : c))
+      : [...state.collections, ...seed.collections],
+    environments: localExisting
+      ? state.environments
+      : [...state.environments, ...seed.environments.filter((e) => e.name === "本地")],
+    activeEnvironmentId: localExisting?.id ?? localEnv?.id ?? state.activeEnvironmentId,
+    history: state.history,
+    settings: state.settings,
+    testCases: hasCase
+      ? state.testCases.map((c) => (c.id === REGRESSION_CASE_ID ? seedCase : c))
+      : [...state.testCases, seedCase],
+    testRuns: state.testRuns,
+    schedules: state.schedules,
+  });
+  return seedCase.id;
+}