hygiene: `.zig-cache-global/` — 376 build-artefact files committed against gitignore rule

[hyperpolymath]

Finding

`.gitignore:25-26` correctly excludes `/zig-out/`, `/.zig-cache/`, `**/.zig-cache-global/`. But `.zig-cache-global/` was committed BEFORE the gitignore rule landed, leaving 376 build-artefact files in git history that are now silently shadowed by gitignore.

Fix

```bash
git rm -r .zig-cache-global/
git commit -m "hygiene: remove pre-gitignore `.zig-cache-global/` build artefacts (376 files)"
```

Then verify the rule actively excludes future re-creation.

Also in scope (related hygiene)

• `test_minimal.cmi` + `test_minimal.cmo` at repo root (OCaml build outputs not in gitignore — `.gitignore` only excludes Coq `.vo*` / `.glob`)
• `src/{ast,parser,typecheck}.cmi/.cmo` (same OCaml debris from #)
• `.tool-versions` is tracked YET `.gitignore:65` says it should be ignored (`# asdf version manager`)

Discovered: 2026-06-01 comprehensive meander audit (entries #80–#82, #119).