test(browser): cover tilde edge cases for executablePath (#71439)

* test(browser): cover tilde edge cases for executablePath

Adds coverage for cases the original tilde-expansion fix in 95a2c9b
intentionally supports but does not assert:

- bare "~" expands to the home directory
- Windows-style "~\AppData\..." expands to $HOME on Windows
- a stray "~" mid-path (e.g. /opt/~chromium/chrome) is preserved verbatim,
  guarding the regex anchor against future regressions

No production code changes; tests only.

* test(browser): skip Windows-style ~\ tilde test on POSIX

path.resolve treats backslashes as literal characters on POSIX, so
"~\AppData\..." cannot resolve to "$HOME/AppData/..." on Linux/macOS.
Gate that case to win32 to keep the assertion meaningful.

extensions/browser/src/browser/config.test.ts

@@ -168,6 +168,39 @@ describe("browser config", () => {
     expect(resolved.executablePath).toBeUndefined();
   });
 
+  it("expands a bare ~ executablePath to the OS home directory", () => {
+    const resolved = resolveBrowserConfig({
+      executablePath: "~",
+    });
+
+    expect(resolved.executablePath).toBe(path.resolve(os.homedir()));
+  });
+
+  // Windows-only: on POSIX path.resolve treats `\` as a literal character,
+  // so "~\foo" cannot resolve to "$HOME/foo". The helper's regex still matches
+  // a leading `~\` on every platform; we only assert the resolved form where
+  // the OS path module agrees.
+  (process.platform === "win32" ? it : it.skip)(
+    "expands a Windows-style ~\\ executablePath to the OS home directory",
+    () => {
+      const resolved = resolveBrowserConfig({
+        executablePath: "~\\AppData\\Local\\Chromium\\chrome.exe",
+      });
+
+      expect(resolved.executablePath).toBe(
+        path.resolve(os.homedir(), "AppData/Local/Chromium/chrome.exe"),
+      );
+    },
+  );
+
+  it("does not expand executablePath values where ~ is not the home prefix", () => {
+    const resolved = resolveBrowserConfig({
+      executablePath: "/opt/~chromium/chrome",
+    });
+
+    expect(resolved.executablePath).toBe("/opt/~chromium/chrome");
+  });
+
   it("normalizes invalid browser tab cleanup numbers to defaults", () => {
     const resolved = resolveBrowserConfig({
       tabCleanup: {