- Updated discriminator test snapshots (3.0.x and 3.1.x) for:
- discriminator-all-of
- discriminator-allof-nested
- transformers-all-of
- Regenerated openapi-ts-fetch example with updated types
- All snapshots now reflect the Omit<> wrapper for discriminator properties

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

- Remove union of child discriminator values from intermediate types
- Each type now gets only its direct discriminator value
- Use Omit<> to remove parent discriminator properties and avoid conflicts
- Enables proper TypeScript type narrowing with discriminated unions

Example: CarDto.$type is now 'Car' instead of 'Car' | 'Volvo'
VolvoDto uses Omit<CarDto, '$type'> & { $type: 'Volvo' }

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

ci: release

feat: Propagate OpenAPI extension fields (x-*) to IR and plugins

- Changed parseExtensions to use Record<string, unknown> instead of any
- Added type assertions at call sites for type safety
- Restored SpecificationExtensions to CallbackObject, PathsObject, ResponsesObject
- Kept PathsObject with [path: /${string}] template literal type
- Extended index signatures with | unknown to satisfy TypeScript

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

Fix discriminator resolution in nested allOf inheritance hierarchies

- Changed parseExtensions to use any types instead of generic constraints
- Removed SpecificationExtensions from interfaces with index signatures (CallbackObject, PathsObject, ResponsesObject)
- Changed PathsObject index signature from /${string} to string for compatibility
- These changes fix TypeScript errors while preserving extension field support

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

- Replaced unnecessary null checks with non-null assertions (!) in for loops accessing array items
- Changed all [] type syntax to Array<T> or ReadonlyArray<T> format for consistency

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>

Co-authored-by: mrlubos <12529395+mrlubos@users.noreply.github.com>