chore(flake): update inputs (#79)

Automated changes by the
[update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock)
GitHub Action.

```
Flake lock file updates:

• Updated input 'llm-agents':
    'github:numtide/llm-agents.nix/5a20300' (2026-05-12)
  → 'github:numtide/llm-agents.nix/a7ad64d' (2026-05-16)
• Updated input 'llm-agents/flake-parts':
    'github:hercules-ci/flake-parts/0678d89' (2026-05-05)
  → 'github:hercules-ci/flake-parts/f7c1a2d' (2026-05-13)
• Updated input 'llm-agents/nixpkgs':
    'github:NixOS/nixpkgs/0a0bf40' (2026-05-12)
  → 'github:NixOS/nixpkgs/d233902' (2026-05-15)
```

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