Re-enable @typescript-eslint once it supports TypeScript 7

We're on typescript@7.0.2, but both `@typescript-eslint/parser` and `@typescript-eslint/eslint-plugin` hard-throw on load against TS 7 (no released version supports it yet), so `eslint.config.mjs` currently ignores all `.ts` files entirely — Prettier still checks their formatting, but ESLint no longer lints them. Once [typescript-eslint/typescript-eslint#10940](https://github.com/typescript-eslint/typescript-eslint/issues/10940) ships TS 7 support, reinstall `@typescript-eslint/parser` + `@typescript-eslint/eslint-plugin` and drop the `**/*.ts` ignore.

Start by checking eslint.config.mjs and the dependency declarations for @typescript-eslint/parser and @typescript-eslint/eslint-plugin after upstream issue 10940 ships TypeScript 7 support. Reinstall compatible versions, remove the **/*.ts ignore, and run the repository's lint and formatting checks to confirm TypeScript files are linted again.

Written by the indexing model from the issue text.