feat: video recording support for --cdp connections

[bentossell]

Problem

agent-browser record start fails with "Browser not launched. Call launch first." when connected to an external Chrome via --cdp. This makes recording unavailable for the common pattern of connecting to a real Chrome instance (e.g. to bypass Cloudflare Turnstile).

Steps to Reproduce

# Launch Chrome with remote debugging
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --remote-debugging-port=9333

# Connect via CDP - works fine
agent-browser --cdp 9333 open https://example.com  # ✓
agent-browser --cdp 9333 snapshot -i               # ✓
agent-browser --cdp 9333 screenshot page.png       # ✓

# Try to record - fails
agent-browser --cdp 9333 record start ./session.webm
# ✗ Browser not launched. Call launch first.

Expected Behavior

Recording should work when connected via CDP, the same way screenshots and all other commands work.

Use Case

When automating sites behind Cloudflare Turnstile, the only reliable approach is connecting to a real Chrome instance via CDP (headless Playwright gets blocked). Recording these sessions for documentation, verification, or demo videos is essential.

Environment

• agent-browser: 0.17.1
• OS: macOS (ARM64)
• Chrome: 147.x

Related

• Request: Support for Cloudflare-protected websites #506 (Cloudflare-protected websites)
• Feature Request: Add stealth mode via AGENT_BROWSER_STEALTH environment variable #120 (stealth mode)
• feat: cookies import command for injecting external cookies #568 (cookie import)