d4191be1

By: Michael Lynch <git@mtlynch.io>

Isolate Go build cache in the dev shell

The dev shell already gives each project a dedicated GOPATH, but it still used the default Go build cache. If another Go version populated that cache, `nix develop --command ./dev-scripts/serve` could fail with errors like:

compile: version "go1.26.1" does not match go tool version "go1.25.5"

Set GOCACHE under the project-specific GOPATH and include the active Go version in the path so development builds do not reuse stale package artifacts from other projects or Go versions.

Testing:
- nix develop --command ./dev-scripts/serve
- dev-scripts/git-hooks/pre-commit
- nix flake check

Timeline