CrabRotation v2.2 - Hybrid CD validation (experimental)

Install: replace Interface/AddOns/CrabRotation folder, /reload.

GCD: Secret Technique uses pre-GCD cached ready state, Dance checks live isActive.
Real Secret Technique cast invalidates its cache via UNIT_SPELLCAST_SUCCEEDED.
The cache must be seeded outside GCD. /crab gcd prints live/effective/source.

Test: Secret ready, Fangs cooling, Dance cooldown shorter than a Backstab GCD, >=6 CP.
During GCD run /crab gcd at early and late points, verify Dance live transition and recommendation.
If Dance live does not transition until GCD ends, the game API masks the CD and the
requested mid-GCD transition cannot be inferred from this boolean alone.

This is an unverified in-game experiment, not a guaranteed fix.
