Major rewrite of DiversityBoost core:
- Replace Butterworth LPF with polynomial frequency modulation
(smooth continuous curve, token-grid normalized via DiT patch_size)
- Add hf_factor, lf_factor, transition parameters for fine control
- Add schedule parameter (flat/linear/cosine) for timestep decay
- Protect near-DC frequencies (r_norm < 1.0) from dc_preserve
to prevent brightness/color shift
- Fix DC handling: step 1+ always preserves full DC
- Support 5D video latents
Rename Core node to V3 (node_id=DiversityBoostCoreV3).
Preserve old node as Legacy (node_id=DiversityBoostCore) for
backward compatibility.
Remove experimental DCW and Smart Patch nodes (superseded by V3).
Aggressive defaults tuned for strong diversity:
strength=2.0, clamp=0.5, hf=1.0, lf=0.3, trans=2.0, sched=linear
