Upgrade 18+ packages including critical axios CVE fix (1.12.2 → 1.15.0),
major bumps for croner (10.x), eslint (10.x), knip (6.x), and minor/patch
bumps across the board. Fix ESLint 10 no-useless-assignment violations.
Add overrides to pin jsdom transitive deps for Jest ESM compatibility.
Resolves all 18 npm audit vulnerabilities (2 critical, 9 high, 7 moderate).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>