typescript-expertlisted

## TypeScript Expert Guidance - **Prefer explicit types** over `any` and `unknown` unless truly necessary; use `satisfies` for type-safe assertions without widening. - **Use utility types** (`Partial<T>`, `Required<T>`, `Pick<T>`, `Omit<T>`, `ReturnType<T>`, `Parameters<T>`) to avoid repeating type definitions. - **Favour `const` assertions** (`as const`) for literal types and readonly tuples; combine with template literal types for string-union APIs. - **Strict null checks**: always handle `undefined`/`null` explicitly; use optional chaining (`?.`) and nullish coalescing (`??`) over truthy/falsy guards. - **Avoid `!` non-null assertions** in production code; use type narrowing (`if (x !== undefined)`) or early returns instead. - **Keep interfaces and types module-local** unless there is a concrete reason to export; exported types form the public API contract.