feat: add Quick Tunnel support for instant public URLs

[lbajsarowicz]

This will become a PR to warden once wardenenv#923 is merged

Summary

Adds Quick Tunnel support on top of the Cloudflare Tunnel integration. Quick Tunnels provide instant public URLs without requiring a Cloudflare account, custom domain, or any setup.

• New WARDEN_QUICK_TUNNEL=1 project-level toggle adds a cloudflared container to the project compose
• Routes through varnish when WARDEN_VARNISH=1, otherwise through nginx directly
• New warden cf quick command extracts and displays the random *.trycloudflare.com URL
• CHANGELOG entry added

How it works

Internet → Cloudflare Edge → quick-tunnel container → varnish/nginx → php-fpm

No login, no credentials, no DNS configuration. Just:

# Add to project .env
WARDEN_QUICK_TUNNEL=1

# Start the project
warden env up

# Get the URL
warden cf quick

Merge path

1. Merge feat: add Cloudflare Tunnel integration wardenenv/warden#923 first (base Cloudflare Tunnel integration)
2. Then merge this PR into the integration branch
3. Then merge the integration branch into main (or create a new upstream PR)

Test plan

• Add WARDEN_QUICK_TUNNEL=1 to a project .env, run warden env up
• Verify quick-tunnel container is running: warden env ps
• Verify warden cf quick shows the *.trycloudflare.com URL
• With WARDEN_VARNISH=1, verify cloudflared routes to varnish
• Without varnish, verify cloudflared routes to nginx
• Without WARDEN_QUICK_TUNNEL, verify no extra container is added