Add 4 new features (WILLR_14, CCI_14, ROC_12, TYPICAL_DEV) and 10 new operators from WorldQuant Alpha 101 + web research.
Alpha 101 core (4): DELTA, TS_ARG_MAX_5, TS_ARG_MIN_5, DECAY_LINEAR_5
Web research supplements (6): SCALE, COVARIANCE_10, PRODUCT_5, SIGNED_POWER_2, TS_DECAY_EXP_5, DELTA_5
Verified: 44/44 operators pass smoke test, 1-step training on forex group succeeds (1.4s). Old strategies remain compatible via VOCAB_VERSION pinning.