mdrop AI access notes

Service: https://mdrop.md
Machine-readable skill: https://mdrop.md/SKILL.md
API discovery endpoint: https://mdrop.md/api/pastes

Recommended flow for agents:
1) Read SKILL.md
2) Self-issue API key via `POST /api/api-keys` (public, rate-limited)
3) Create markdown via POST /api/pastes with `Authorization: Bearer mdk_...`
4) Return preview_url/raw_url/telegraph_url to user (`instant_view_url` is intentionally null)
5) Use PATCH /api/pastes/:id for edits
6) Use DELETE /api/pastes/:id for cleanup