feat: Add Webhooks CLI and Signature Verification Utils

[maticzav]

This PR adds two utility methods for verifying Browser Use Webhook signatures and parsing the payloads.

verifyWebhookEventSignature(
  evt: {
    evt: string;
    signature: string;
    timestamp: string;
  },
  cfg: { secret: string },
): Promise<{ ok: true; event: Webhook } | { ok: false }>

createWebhookSignature({
  payload,
  timestamp,
  secret,
}: {
  payload: unknown;
  timestamp: string;
  secret: string;
}): string

Additionally, this PR creates a listen CLI utility that helps with local development.

[delve-auditor]

✅ No security or compliance issues detected. Reviewed everything up to 7afd50c.

Security Overview

• 🔎 Scanned files: 14 changed file(s)

Detected Code Changes

Change Type	Relevant files
Configuration changes	► examples/.env.example     Add environment variables configuration example
Enhancement	► examples/utils.ts     Add dotenv configuration support ► examples/webhook.ts     Add webhook example implementation ► src/lib/webhooks.ts     Add webhook functionality ► src/lib/bin/cli.ts     Add CLI implementation ► src/lib/bin/auth.ts     Add authentication utilities ► src/lib/bin/commands/listen.ts     Add listen command functionality
Refactor	► examples/demo.ts ► examples/stream-zod.ts ► examples/stream.ts ► examples/zod.ts     Update to use environment configuration

Reply to this PR with @delve-auditor followed by a description of what change you want and we'll auto-submit a change to this PR to implement it.

[delve-auditor]

✅ No security or compliance issues detected. Reviewed everything up to f9bf0a1.

Security Overview

• 🔎 Scanned files: 8 changed file(s)

Detected Code Changes

Change Type	Relevant files
Enhancement	► webhook.ts     Add webhook example implementation ► webhooks.ts     Add webhook verification and signature functionality ► auth.ts     Add BrowserUse client authentication ► cli.ts     Add CLI base command handler ► listen.ts     Add webhook listen command
Configuration changes	► package.json     Add CLI dependencies and binary configuration

Reply to this PR with @delve-auditor followed by a description of what change you want and we'll auto-submit a change to this PR to implement it.