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>

- Created SpecificationExtensions interface in 3.0.x and 3.1.x spec.d.ts
- Applied to all 27 interfaces that support extensions in each version
- Replaced inline `[extension: x-${string}]: unknown` with extends clause
- Also added SpecificationExtensions to JsonSchemaDraft2020_12

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

- Changed DiscriminatorInfo.values type from string[] to ReadonlyArray<string> to match discriminatorValues return type
- Added null check for array item access to prevent possibly undefined errors
- Changed required array mutation from push to spread operator to work with readonly arrays

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