feat: update flake.lock (#101)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/8eaee110344796db060382e15d3af0a9fc396e0e?narHash=sha256-iCGWf/LTy%2BaY0zFu8q12lK8KuZp7yvdhStehhyX1v8w%3D' (2025-09-19)
  → 'github:nixos/nixpkgs/e643668fd71b949c53f8626614b21ff71a07379d?narHash=sha256-NY3kSorgqE5LMm1LqNwGne3ZLMF2/ILgLpFr1fS4X3o%3D' (2025-09-24)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]