docs: add Vercel Setup guide, cross-link from Cloudflare/Fastly Vercel had no dedicated setup guide even though it's the default provider — general instructions were folded into Getting-Started.md while Cloudflare and Fastly each got their own thorough guide (credentials, day-to-day commands, provider quirks, troubleshooting, security). Adds parity, verified against real CLI source (init.ts, VercelProvider.ts, providerHelper.ts, promptForCredentials.ts, setup.ts) rather than copied from the other guides' assumptions. Notably documents that VERCEL_TEAM_ID is required in practice today, despite setup.ts/README describing it as optional for personal accounts — the runtime throws if it's missing.
docs: add Fastly Next-Gen WAF coverage New Fastly-Setup and Fastly-Migration pages mirroring the existing Cloudflare ones, registered in the sidebar. Updated Home, Getting-Started, Configuration, Commands-Overview, and CI-CD-Integration to mention Fastly alongside Vercel/Cloudflare wherever they previously only covered two providers — condition type/operator/action compatibility tables, env vars, CLI examples, and the multi-provider CI pipeline example. Companion to gfargo/doorman#204/#205 (Fastly provider adapter).