Add boolean schemas and raw schema escape hatch

[crmne]

Goal

Add support for boolean schemas and a raw schema escape hatch.

JSON Schema allows a schema itself to be a boolean:

• true means every value is valid.
• false means no value is valid.

Example:

true

accepts anything.

false

rejects everything.

Boolean schemas can also appear inside composition:

{
  "anyOf": [
    true,
    { "type": "string" }
  ]
}

Proposed DSL

any_of :value do
  any_schema
  string
end

none_of :value do
  no_schema
end

Raw escape hatch

raw :value, {
  "type" => "string",
  "const" => "admin"
}

Acceptance criteria

• Boolean schemas work anywhere subschemas are accepted.
• Raw schema fragments are preserved and normalized.
• Generated schemas validate against Draft 2020-12 when fragments are valid.