Warp open-sources docs, maintenance agents

This is less a docs migration than a statement about Warp's operating model: the docs are now part of the product's AI loop, not a side asset.

• –Warp says the docs feed the context layer behind Warp Agent through RAG, so stale docs directly degrade both human and agent output
• –The new stack uses Astro and Starlight, with Markdown-in-GitHub so changes are readable, forkable, and easier to review
• –Several maintenance jobs are now agent-driven, including PR review, changelog updates, broken-link sweeps, and SEO/AEO audits
• –For developers, this is a practical example of using open source to make an AI product easier to extend, audit, and contribute to
• –It also reinforces Warp's broader bet that agent workflows should be visible and collaborative, not hidden behind closed tooling