api/dist/ (468 files, 11MB) and admin/tsconfig.tsbuildinfo were committed
before being added to .gitignore — the rule had no effect on the existing
tracked copies. Untrack them now so future Docker rebuilds stop showing
spurious diffs. Files stay on disk; rebuild regenerates everything.
Also add *.tsbuildinfo to .gitignore so future tsc incremental caches stay
out of git.