Convert the routinely-used environment knobs to command-line flags (the
canonical interface); the REDBEAR_*/JOBS env vars remain deprecated fallbacks.
New flags: -j/--jobs, --release VER, --allow-dirty, --keep-build-state
(--upstream/--no-cache already existed). Resolved values are re-exported so the
gates and sub-scripts observe them. Rare escape hatches stay env-only and are
documented under an 'Advanced' section in --help. Dropped the phantom
REDBEAR_SKIP_ABI_STALENESS doc; did not add --arch/--target (x86_64-only build).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
vasilito
0486839dd0