K4 made BlockExplodeProjected address storage through block_ddf and
block_slot (core/layout.cuh). This host test compiles the kernel text
extracted from blocks.cu, so it now also extracts those two helper
definitions from core/layout.cuh (device qualifiers -> inline) instead of
failing to compile. Assertions and tolerances unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>