feat!: make Standard Schema integration schema-first

[kauandotnet]

Summary

• reposition the package around schema-first validation, serialization, and OpenAPI integration
• make raw Standard Schemas first-class and add optional request/response schema classes for Nest runtime reflection
• replace the DTO-era public API, plugin diagnostics, examples, and documentation with schema-class terminology
• remove the deprecated Swagger array adapter and add a breaking minor Changeset

Breaking changes

• replace createStandardSchemaDto with createSchemaClass
• replace createStandardSchemaResponseDto with createResponseSchemaClass
• replace StandardSchemaDtoValidationPipe with SchemaClassValidationPipe
• remove all compatibility aliases for the 0.1 alpha API

Verification

• pnpm run check
• pnpm run test
• pnpm run test:typescript7
• pnpm run verify:pack
• pnpm dlx madge --circular --extensions ts,cts src