Publish Haskell bindings to Hackage

[jupblb]

Wires up Haskell binding publication to Hackage. Adds a publish-haskell-bindings job to release.yaml (alongside the existing Rust/JVM/Go publish jobs) and prepares bindings/haskell/scip.cabal for Hackage with proper metadata bounds, a source-repository pointer, and GHC2024 as the default language.

Post-merge: claim the scip name on Hackage

Hackage versions are immutable — once 0.7.1 is published it can never be re-uploaded. The first publish therefore goes through the candidate channel so we can preview the rendered package page before committing.

From a maintainer's machine on main:

cd bindings/haskell
nix develop -c cabal sdist
nix develop -c cabal upload --token="$HACKAGE_TOKEN" \
    dist-newstyle/sdist/scip-0.7.1.tar.gz

Review the candidate at https://hackage.haskell.org/package/scip-0.7.1/candidate — verify the rendered README, that the source-repository link targets bindings/haskell, the license is detected as Apache-2.0, and the dependency bounds look right.

When satisfied, publish:

nix develop -c cabal upload --publish --token="$HACKAGE_TOKEN" \
    dist-newstyle/sdist/scip-0.7.1.tar.gz

(Or click Publish candidate on the Hackage UI.)

This claims the scip name for the Hackage account behind HACKAGE_TOKEN and seeds the maintainer group with that account. From the next release onwards the workflow handles publication automatically.