chore(flake): update inputs

Flake lock file updates:

• Updated input 'llm-agents':
    'github:numtide/llm-agents.nix/a7ad64d' (2026-05-16)
  → 'github:numtide/llm-agents.nix/468bacd' (2026-06-01)
• Updated input 'llm-agents/bun2nix':
    'github:nix-community/bun2nix/2499ded' (2026-05-10)
  → 'github:nix-community/bun2nix/f2bc12a' (2026-05-10)
• Updated input 'llm-agents/nixpkgs':
    'github:NixOS/nixpkgs/d233902' (2026-05-15)
  → 'github:NixOS/nixpkgs/e9a7635' (2026-05-29)
• Updated input 'llm-agents/treefmt-nix':
    'github:numtide/treefmt-nix/790751f' (2026-04-08)
  → 'github:numtide/treefmt-nix/db94781' (2026-05-31)

Author: github-actions[bot]