prefect server in zig

ci: add gnugrep and coreutils to nix deps

test scripts use grep, tr, kill, sleep, etc.

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

+2
+2
.tangled/workflows/ci.yml
··· 9 9 - zig 10 10 - curl 11 11 - bash 12 + - gnugrep 13 + - coreutils 12 14 - postgresql 13 15 - redis 14 16