Midnight exp_11: Deep targets — CIV detrend kills multi-ion signal

CRITICAL HONEST FAILURE: CIV intra-doublet signal (KS=0.21, p~0) does
NOT survive z-detrending. Raw rho=-0.592 drops to rho=0.057 (p=0.68)
after quadratic detrend. Same z-confound pattern as MgII EW spread.
The multi-ion confirmation was a z-trend artifact.

Spatial dipole: not significant (75th percentile), opposite direction
from Webb alpha dipole (178 deg separation).

Entropy gradients: EW and FWHM gradients are physically correlated
(rho=0.462, p~0) — when one increases, so does the other. Gradient
sightlines are spatially clustered (p=0.002). 53/47 split between
increasing and decreasing. This is real structure, not cascade-specific.

What survives ALL controls after 11 experiments:
- Sightline-straddling pairs (z-trend immune, p~0)
- Narrow-window doublet coherence (z-trend immune, p=1e-4)
- Entropy gradients 2x random (structural, not cascade)
- EW-FWHM gradient coherence (physical, rho=0.46)

Author: lornecodes