fix(cli): keep doctor resilient to a corrupt browser cache (#1822)

* fix(cli): keep doctor resilient to a corrupt browser cache

A partial or corrupt browser cache (a stub file where a version directory
is expected, a missing executable, or malformed metadata) makes
getInstalledBrowsers throw ENOTDIR. That throw propagated up through
findBrowser -> checkChrome -> runEnvironmentChecks, and since doctor.run
calls runEnvironmentChecks before any try/catch or the --json output, the
command crashed with exit 1.

doctor --json is documented to exit 0 even when checks fail, so it must
report a corrupt cache as "Chrome not found", not crash on it.

- checkChrome now catches any error from findBrowser and converts it to the
  existing ok:false "Chrome not found" outcome with the browser ensure hint,
  so runEnvironmentChecks never throws for a missing or corrupt browser.
- findFromCache treats a throwing getInstalledBrowsers as "no cached
  browser", letting resolution fall through to system/download instead of
  crashing every caller (render included), not just doctor.

A healthy browser still reports ok:true. Adds a preflight test asserting an
ok:false Chrome outcome when discovery throws, instead of propagating.

* fix(cli): warn on corrupt browser cache fallback

packages/cli/src/browser/preflight.test.ts

@@ -1,6 +1,7 @@
 // fallow-ignore-file code-duplication
-import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { parseToolVersion, runEnvironmentChecks } from "./preflight.js";
+import * as manager from "./manager.js";
 
 describe("runEnvironmentChecks", () => {
   const originalFfmpegPath = process.env.HYPERFRAMES_FFMPEG_PATH;
@@ -67,6 +68,27 @@ describe("runEnvironmentChecks", () => {
     });
   });
 
+  it("reports Chrome as not found (no throw) when browser discovery throws on a corrupt cache", async () => {
+    const spy = vi.spyOn(manager, "findBrowser").mockRejectedValue(
+      Object.assign(new Error("ENOTDIR: not a directory, scandir 'chrome-headless-shell'"), {
+        code: "ENOTDIR",
+      }),
+    );
+
+    try {
+      const result = await runEnvironmentChecks({ includeBrowser: true });
+
+      expect(result.outcomes.find((outcome) => outcome.name === "Chrome")).toMatchObject({
+        ok: false,
+        title: "Chrome not found",
+        hint: "Run: npx hyperframes browser ensure",
+      });
+      expect(result.browser).toBeUndefined();
+    } finally {
+      spy.mockRestore();
+    }
+  });
+
   it("reports an explicit missing browser path before render starts", async () => {
     const result = await runEnvironmentChecks({
       includeBrowser: true,