Add flake

[deemp]

• Add flake.nix
• Add direnv config
• Add fourmolu config
• Format code

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PR-Codex overview

Focus of this PR:

Update dependencies, fix imports, and improve code formatting.

Detailed summary:

• Update the eo-phi-normalizer package version and license.
• Update the license in the eo-phi-normalizer.cabal file.
• Update the fourmolu.yaml file for code formatting.
• Update the flake.nix file for dependency management.
• Fix imports and reorganize code in Language.EO.PhiSpec.hs.
• Fix imports and reorganize code in Test.EO.Phi.hs.
• Fix imports and reorganize code in Language.EO.Phi.Normalize.hs.
• Fix imports and reorganize code in Language.EO.Phi.Syntax.Abs.hs.

The following files were skipped due to too many changes: flake.nix, eo-phi-normalizer/src/Language/EO/Phi.hs, eo-phi-normalizer/src/Language/EO/Phi/Syntax/Print.hs

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