feat: update flake.lock (#102)

Flake lock file updates:

• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/e643668fd71b949c53f8626614b21ff71a07379d?narHash=sha256-NY3kSorgqE5LMm1LqNwGne3ZLMF2/ILgLpFr1fS4X3o%3D' (2025-09-24)
  → 'github:nixos/nixpkgs/7df7ff7d8e00218376575f0acdcc5d66741351ee?narHash=sha256-gTrEEp5gEspIcCOx9PD8kMaF1iEmfBcTbO0Jag2QhQs%3D' (2025-10-02)

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Author: github-actions[bot]