TypeScript 5 → 7 upgrade

TypeScript 5 → 7 upgrade for an open-source TypeScript CLI tool, done in two steps (5 → 6 → 7): compiler option changes, new type errors fixed, tooling updated. 1177/1177 tests passing before and after, build and type check green, CI parity table in the PR. The maintainer closed it to fold the change into their own upcoming PR — the diff and verification are public in the link.