feat(website): move MCP guide into docs

[jog1t]

Standalone version of #42, rebased off main so it no longer depends on the MCP landing page stack (#20).

Summary

• moves the Rivet MCP guide into the shared docs experience at /docs/mcp/
• adds the shared AI Tools group to every product documentation sidebar while preserving each product's docs context
• adds accessible client setup tabs with client logos, copy feedback, and a no-JavaScript fallback
• preserves MCP scope, security, examples, metadata, Markdown exports, footer link, and service routing

Differences from #42

Ejecting from the stack required three conflict resolutions:

• Caddyfile — took this branch's MCP block (main had none) while keeping main's newer HTML no-cache rules. The mcp.rivet.dev host block originated in feat(website): add the MCP landing page #20 and is carried here so the /mcp → /docs/mcp/ redirect doesn't intercept the MCP service endpoint.
• src/components/v2/Code.tsx — kept main's hover-reveal toolbar (opacity-0 … group-hover/code:opacity-100).
• src/layouts/BaseLayout.astro — kept both preconnectAssets (from main) and exactTitle (from this change).

The src/pages/mcp.astro deletion drops out cleanly, since that file only exists on the landing-page branch.

Validation

• production build passes on this branch: 445 pages, /docs/mcp/ renders

[railway-app]

🚅 Deployed to the website-pr-43 environment in rivet-website

Service	Status	Web	Updated (UTC)
website	😴 Sleeping (View Logs)	Web	Sep 1, 2026 at 11:59 pm