fix(browser-use): record sessions through V4

[MagMueller]

What

• honor BrowserArena’s existing recording option when creating Browser Use sessions
• use the Browser Use V4 browser resource to create, stop, and retrieve recordingUrl
• add three mocked HTTP regression tests for create, recording download, and stop

Why

BrowserArena’s record command already calls provider.create({ recording: true }), but BrowserUseProvider ignored that flag. It also polled the V3 agent-session resource, which is not the browser record that owns recordingUrl. The result was a Browser Use run without an available proof video.

This patch sends enableRecording to V4 and reads the V4 browser record after the run stops.

Validation

• npm ci
• npm run build
• node --import tsx --test src/providers/browser-use.test.ts (3 passed)
• git diff --check
• TruffleHog: 0 verified or unverified secrets
• current Browser Use V4 OpenAPI checked for create, get, stop, recording, and status fields

All HTTP tests are mocked. I did not use a real API key or start a paid browser session.

[greptile-apps]

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