Repository lint could silently miss private headers in srcs when an older Buildozer on PATH printed package-less target labels. SharedTools.buildozer in buildscripts/quality_checks/adapters.py now always resolves the installer’s pinned version, which verifies cached binaries and replaces stale ones. Regression tests cover ignoring PATH, reusing the installed binary, and unsupported platforms.

Move parallelism_planner_test_fixture.h from srcs to private_hdrs for required_distribution_test and parallelism_planner_test, so both targets pass the restored check.