CLAUDE: CuasLogFold - LoG-into-kernel fold + synthetic impulse/grating self-test (roadmap RT-seed step 1)

Findings (all validated to stated precision by the self-test, exit 0):
- Per-bin TD quad-multiply == pixel convolution with cos(pi*dx/16)*cos(pi*dy/16)
  ATTENUATED taps (matches norm_sym_weights in calculateCLTKernel; shift-tap
  error exactly 1-cos(pi/16) before compensation). getLogTd() therefore
  pre-compensates LoG taps by 1/cosAtten so the EFFECTIVE filter is the true
  pixel LoG (machine-exact at non-bin gratings).
- Residual floors: symmetric-extension wrap ~0.5-2.5% (inherent to the lapped
  structure); folded-vs-pixel-LoG A/B cross-term ~7% on a pessimistic spread
  kernel (test 5 - predicts the full-run A/B floor).
- clt_symmetrize_kernel quadrant-3 (AA) sign pattern looks like a latent
  copy-paste of the AS expression: pure-AA kernel test - math sign 2.6e-3,
  code sign 1.9e-1. Production kernel files likely carry the wrong AA sign.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>