0.4.6 — cache-path entry points honor the zero-dep-core contract

A plain pip install gate-cat gives a zero-dependency veto. This release makes the cache-side tools degrade as gracefully as the core already promised.

• gatecat-cli no longer crashes with a raw ModuleNotFoundError: numpy — it prints install gate-cat[cache] and exits cleanly. Bonus: gatecat-cli audit (which runs against your endpoint, not the cache) now works without the cache stack.
• from gatecat import CachedOpenAI / CachedAnthropic without the deps now name the right extra (missing numpy → [cache], missing openai → [openai]), not a raw traceback.
• +6 regression tests. The veto path was already clean and is unchanged.

FACTS F9 → 0.4.6.