PDOCS-4764: Add MicroVMs Public Preview API

[beardicus]

Summary

Adds the MicroVMs API for the public preview launch on 2026-10-09, under a new MicroVMs [Public Preview] tag in the Public APIs group. This covers 13 operations: list, create, get, delete, pause, resume, exec, console, options, plus checkpoint create, list, get, and delete.

The spec is adapted from the private preview API doc and checked against the live API on 2026-10-08.

Jira: PDOCS-4764

Verified against the live API

• Create returns 201, delete returns 204.
• Pause returns 200 with the microvm object, including when the MicroVM is already paused.
• Checkpoint create returns 201 with the checkpoint object in CHECKPOINT_CREATING. Checkpoint delete returns 204.
• Error codes in the examples are observed values: INVALID_SIZE, INVALID_AUTO_PAUSE, FAILED_PRECONDITION (deleting a checkpoint that is still capturing), and NOT_FOUND.
• http_protocol is null in responses when it is not set at creation, so the response schema marks it nullable.

Needs engineering confirmation

• Resume. Not verified. Resume returned 503 during testing, and new MicroVMs in MKC1 failed to start. I assumed it mirrors pause (200 with the microvm object).
• Gateway errors. The 503 came back as {"id": "Service Unavailable", "message": "Server Error"}, not the {"code", "message"} shape. Gateway-level errors can use the standard DigitalOcean API error body.
• 403 and 502 codes. I didn't observe these. The PERMISSION_DENIED and UNAVAILABLE examples are still guesses.
• Console. GET /v2/microvms/{microvm_id}/console documents a 101 Switching Protocols WebSocket upgrade. Spectral warns that it has no 2xx response, the same warning the existing gen-ai/models/api_keys operation already has.
• Tag name. The tag follows the VPC Routes [Public Preview] precedent, so the tag slug changes when the suffix is dropped at GA.

Test plan

• make lint: 0 errors. The only new warning is the console one above.
• The bundle has no schema renames from the new MicroVMs files.

[apinonformoso]

LGTM, Paths and methods match the mvm product publicapi implementation 1:1