feat: Emit format-based validation attributes for email and phone

[nikcio]

Changes

Emit for and for when is enabled. These are standard attributes used by ASP.NET Core model validation.

Example

User:
  type: object
  properties:
    email: { type: string, format: email }   -> [EmailAddress]
    phone: { type: string, format: phone }   -> [Phone]

Implementation

• Add helper to map string formats to validation attributes
• Update to detect format-based attributes so is emitted
• Suppressed when is passed (existing option)
• Other formats (nikcio-desktop, , , , ) remain plain — no standard validation attributes fit without adding dependencies

Testing

All 276 tests pass (266 existing + 5 new). New tests include compilation with .