Fix security vulnerabilities in tar dependency

- Update electron-builder from 24.13.3 to 26.5.0
- Add npm override to force tar@^7.5.6
- Fixes GHSA-8qq5-rm4j-mr97 (path sanitization)
- Fixes GHSA-r6q2-hw4h-h46w (race condition on macOS APFS)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: steveseguin