Upgrade ESLint to v10

Updated ESLint from v9.39.4 to v10.1.0 (latest).

ESLint 10 is fully compatible with the existing flat config format
and all plugins continue to work as expected.

Note: eslint-plugin-import shows a peer dependency warning as it
doesn't officially declare support for ESLint 10 yet, but it works
correctly without issues.

Result:
- ESLint v10.1.0 installed
- All linting passing
- All tests passing
- Production build working
- 0 vulnerabilities

Author: dduugg