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/execution.test.ts

@@ -0,0 +1,31 @@
+import { describe, expect, it, vi } from "vitest";
+import { executeOnce, useTestExecution } from "./execution";
+
+describe("shared test execution", () => {
+  it("shares a pending run across entry points and releases it after completion", async () => {
+    let resolve!: (value: string) => void;
+    const task = vi.fn(() => new Promise<string>((r) => { resolve = r; }));
+    const first = executeOnce("case-1", task);
+    const second = executeOnce("case-1", task);
+    expect(first).toBe(second);
+    expect(useTestExecution.getState().running.has("case-1")).toBe(true);
+    await Promise.resolve();
+    expect(task).toHaveBeenCalledTimes(1);
+    resolve("report");
+    await expect(first).resolves.toBe("report");
+    expect(useTestExecution.getState().running.has("case-1")).toBe(false);
+    await expect(executeOnce("case-1", async () => "new report")).resolves.toBe("new report");
+  });
+
+  it("clears failed runs and allows retry without clearing other active cases", async () => {
+    let resolve!: () => void;
+    const other = executeOnce("other", () => new Promise<void>((r) => { resolve = r; }));
+    await expect(executeOnce("failed", () => { throw new Error("transport unavailable"); }))
+      .rejects.toThrow("transport unavailable");
+    expect([...useTestExecution.getState().running]).toEqual(["other"]);
+    await expect(executeOnce("failed", async () => "retry")).resolves.toBe("retry");
+    resolve();
+    await other;
+    expect(useTestExecution.getState().running.size).toBe(0);
+  });
+});