Raise Canny thresholds 120/240 -> 150/300 to clear residual stray marks

User review of the previous fix's output at higher zoom caught small
isolated stray marks (forehead, eyebrow tip, under-lip) still present on
jason_a -- the 120/240 threshold wasn't quite enough on its own. With the
LoRA's own line-drawing already suppressed (prior commit), the residual
cause is tiny high-contrast points in the Iray render (specular
highlights, skin pores) still exceeding 120/240 in isolated spots.
150/300 clears them; tested against 200/400 and a bilateral-filter
pre-smoothing pass, both equally effective but no better, so kept the
simpler/more conservative plain threshold change. Re-verified through
the production CLI on both jason_a and abby_b.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: ghirpara