Resolve the TODO that appears in the generated docs/content/reference/api.md at line 3762: "TODO: What is the valid character set for this field?" for the imageID field.

The docs file is auto-generated by make api-docs, so the TODO originates in the API Go type definitions under api/. The fix must be made in the API type comments, then regenerated with make api-docs.

Why

The API reference does not explain the expected format for the imageID field. Users need to know that this must be a full Azure resource ID (e.g., /subscriptions/.../resourceGroups/...) and any size constraints so that validation errors are clearer.

Acceptance Criteria

• Locate the TODO in the API Go type definition under api/ that produces this generated doc text
• Update the Go type comment to document that imageID must be a full Azure resource ID
• Include an example of the expected format
• Note any size constraints
• Remove the TODO comment from the API source
• Run make api-docs to regenerate the documentation

Technical Details

• Generated file: docs/content/reference/api.md line 3762
• Source: API Go type definitions under api/ (find the TODO matching this field)
• TODO text: "TODO: What is the valid character set for this field?"
• Context: Azure imageID field in the API spec
• Regenerate: make api-docs