browser: add Windows Chrome executable detection

src/browser/chrome.test.ts

@@ -8,6 +8,7 @@ import { afterEach, describe, expect, it, vi } from "vitest";
 import {
   decorateClawdProfile,
   findChromeExecutableMac,
+  findChromeExecutableWindows,
   isChromeReachable,
   stopClawdChrome,
 } from "./chrome.js";
@@ -155,6 +156,34 @@ describe("browser chrome helpers", () => {
     exists.mockRestore();
   });
 
+  it("picks the first existing Chrome candidate on Windows", () => {
+    const exists = vi
+      .spyOn(fs, "existsSync")
+      .mockImplementation((p) => String(p).includes("Chrome SxS"));
+    const exe = findChromeExecutableWindows();
+    expect(exe?.kind).toBe("canary");
+    expect(exe?.path).toMatch(/Chrome SxS/);
+    exists.mockRestore();
+  });
+
+  it("finds Chrome in Program Files on Windows", () => {
+    // Use path.join to match how the function builds paths (cross-platform)
+    const marker = path.join("Program Files", "Google", "Chrome");
+    const exists = vi
+      .spyOn(fs, "existsSync")
+      .mockImplementation((p) => String(p).includes(marker));
+    const exe = findChromeExecutableWindows();
+    expect(exe?.kind).toBe("chrome");
+    expect(exe?.path).toMatch(/chrome\.exe$/);
+    exists.mockRestore();
+  });
+
+  it("returns null when no Chrome candidate exists on Windows", () => {
+    const exists = vi.spyOn(fs, "existsSync").mockReturnValue(false);
+    expect(findChromeExecutableWindows()).toBeNull();
+    exists.mockRestore();
+  });
+
   it("reports reachability based on /json/version", async () => {
     vi.stubGlobal(
       "fetch",