fix: lazy-load cloudflare:workers to support non-Worker runtimes

[LordCoughmann]

Problem

The top-level import { env } from 'cloudflare:workers' causes the module to crash when loaded in non-Worker runtimes (Node.js, Deno, Bun, browsers). This prevents using connectOverCDP() with external CDP endpoints outside of Cloudflare Workers.

Reproduction: https://github.com/LordCoughmann/repo-cf-playwright-lazy-import

pnpm install
node index.mjs
# → Error [ERR_UNSUPPORTED_ESM_URL_SCHEME]: Only URLs with a scheme in: file, data, and node are supported

Solution

Replace the static import with a lazy getter that resolves cloudflare:workers only when Browser Binding functions are actually called:

let _env: Record<string, any> | null = null;
function getEnv(): Record<string, any> {
  if (_env === null) {
    try {
      const { createRequire } = require('node:module');
      const cjsRequire = createRequire(import.meta.url);
      _env = cjsRequire('cloudflare:workers').env ?? {};
    } catch {
      _env = {};
    }
  }
  return _env;
}

• In Workers: resolves normally, no behavior change
• Outside Workers: falls back to {}, module loads successfully
• env is only accessed by endpointURLString() and getBrowserBinding() — functions only called for Browser Binding workflows
• Call-site errors unchanged: No binding found for ${binding} still fires if someone uses Browser Binding without a valid binding

We've been using @cloudflare/playwright@1.3.0 patched with this pattern in production with external CDP endpoints (Steel, Browserbase, local Chrome) and test environments (Node.js + Vitest).

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I understand this is likely not a priority for the team. Happy to adjust the approach, or maintain this as a downstream patch if that's preferred. Any feedback welcome.

Refs: #88, #59