Partial diff: added / removed operations, renames, and spec-info fields. Nested schema changes are not tracked yet.

2026-04-2243cbd6ddocs: add playground page, refresh mock spec to 2.0.1

2026-04-20c5fe53edocs: refresh mock spec from api.rodin.dev

Description changedlogin"Authenticate with email/password. Mock: any password works. Token valid 1 hour." → "Authenticate with email/password. Mock: any password works for any seeded email. The demo account demo@example.com is always present and carries admin role — use it for docs Try-It. Token valid 1 hour."
Description changedechoPost(none) → "Mirror the request body, query, and headers back — handy when you want to see exactly what your client is sending."
Description changedmockUpload"Simulates upload — no actual file storage." → "Simulates upload — no actual file storage. Accepts raw binary, multipart form, or JSON with a filename hint. Returns a fake CDN URL so your frontend can wire the full happy path without real object storage."