zig-toolchain

Use before running any zig command on this Mac, and when asked which Zig is active, what version a repo targets, where the stdlib source lives, how to read Zig docs, what zig std serves, why two zig binaries disagree, or where to put build and test scratch. Covers zvm layout, the dangling current symlink, the Homebrew nightly cask beside zvm, and the iCloud scratch rule.