typst: add initial support for typst packages

[cherrypiejam]

This PR adds initial support to build Typst documents with Typst packages. In particular, it adds a Typst package builder and exposes it at the top level to ease the process of defining new Typst packages. It further adds a new function to the Typst derivation for creating a new Typst environment in which the Typst compiler understands a specific set of packages, namely typst.withPackages. Moreover, three Typst packages are defined and collected as a single attribution set as an initial demonstration.

Only a few Typst packages are included in this PR for a reason. The Typst Universe (the official site for Typst packages) maintains a single git repo that contains all Typst packages. Each package entry does not necessarily map to the same version specified in their respective git repo published by their authors (if there is). This is because the package authors need to manually move their package and copy the source, instead of a pointer, to the Typst Universe repo. Breaking the Typst Universe repo down to per package requires separate places to store each of them, and due to the aforementioned reason, the exact source may disagree with the original git repo ¹. This is why, in my opinion, we might want to collect our own set of Typst packages instead of directly pulling from the Typst Universe repo. For gradual adaption, typst.withPackages also provides a method to override the predefined set of Typst packages, namely typst.withPackages.override, making it easier for end users overriding the existing set of Typst packages and integrating new packages into their project.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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Footnotes

1. Assuming the author(s) also publish their package in another repo outside of the Typst Universe repo. ↩

[SigmaSquadron]

Welcome to Nixpkgs! This is truly amazing; I've wanted to build Typst packages for a very long time but never got around to it.

Note that the commits should be split as much as possible. Each new typstPackage should be added in a separate commit. The changes to the base typst package to wrap it should also be a separate commit.