Issue Description

The schema at scripts/linting/schemas/agent-frontmatter.schema.json is missing fields and has incorrect type definitions compared to VS Code's official custom agents specification.

Missing Fields to Add:

Type Definitions to Fix:

Schema Additions:

{
  "agents": {
    "oneOf": [
      { "type": "array", "items": { "type": "string" } },
      { "type": "string", "enum": ["*"] }
    ]
  },
  "model": {
    "oneOf": [
      { "type": "string" },
      { "type": "array", "items": { "type": "string" } }
    ]
  },
  "user-invokable": { "type": "boolean", "default": true },
  "disable-model-invocation": { "type": "boolean", "default": false }
}

Handoffs Item Update:

• Change required from ["label", "agent", "prompt"] to ["label", "agent"]
• Add model property (optional string)

Additional Context

• Keep HVE-Core specific maturity field (extension channel control)
• VS Code reference:
• All existing agent files pass current schema; changes are additive except handoffs.prompt becoming optional