Add cloud-init and vsock to the VM manifest #106

Summary

Make cloud-init provisioning and vsock management first-class manifest features for Stack and Ultramarine Server workloads.

Scope

• Define cloud-init user-data/metadata/vendor-data fields.
• Generate the required Cloud Hypervisor configuration.
• Define vsock devices, CID allocation, and collision handling.
• Expose resulting vsock configuration through VM info.
• Document guest-side agent expectations and firmware/image limitations.

Tasks

• Define cloud-init user-data, metadata, and vendor-data fields in the VM manifest.
• Define how cloud-init data is transported to the guest.
• Generate the required Cloud Hypervisor cloud-init configuration.
• Define vsock device fields and CID allocation behavior.
• Implement collision-safe CID allocation and persistence.
• Convert vsock manifest data to VsockConfig.
• Expose effective cloud-init and vsock configuration through VM info.
• Document guest-side agent expectations and firmware/image limitations.
• Update the in-development VM manifest and callers directly instead of adding compatibility for older Odorobo formats.
• Add cloud-init and vsock conversion tests.
• Identify which Proxmox guest metadata must be translated into the new Odorobo manifest during migration.

What this should do

• A VM can request cloud-init entirely through its Odorobo manifest.
• A VM can request a vsock device declaratively.
• CID assignment is collision-safe and has defined restart behavior.
• Cloud-init and vsock conversion tests exist.
• The post-migration cloud-init and vsock contract is documented for Stack and Ultramarine Server.

Dependencies

• Depends on draft issues 01 and 02.

Related issues

• Refines Metadata Service #25 (Metadata Service) and Generate cloud-init/Ignition configs #26 (cloud-init/Ignition configs).
• Must account for Cloud-Hypervisor RVA23 Support #29 (RVA23 support).

Issue links

• Depends on #98 and #99.
• Related to existing #25, #26, and #29.
• Enables #107.