feat(decorator): add type definition for format option

[mag123c]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

The format field in @ApiProperty() accepts any string value, which allows for invalid or misspelled values without any feedback from the TypeScript compiler.

Issue Number: #3508

What is the new behavior?

Added SchemaObjectFormat type that

• Provides IDE autocomplete for OpenAPI-defined standard formats (int32, int64, float, double, byte, binary, date, date-time, password)
• Includes commonly used formats (email, uuid, uri, hostname, ipv4, ipv6)
• Maintains full backward compatibility by allowing custom format values via (string & {}) pattern

@ApiProperty({ format: 'date-time' })  // Autocomplete + type checking
createdAt: Date;

@ApiProperty({ format: 'custom-format' })  // Still works (backward compatible)
customField: string;

The (string & {}) pattern ensures all existing custom format values continue to work while providing autocomplete for standard formats.

Does this PR introduce a breaking change?

• Yes
• No