preload_vector and preload_weights wrote using base as a word address
instead of a byte address (base + (k>>1) instead of (base>>1) + (k>>1)),
misaligning X/W data in PSRAM relative to what int8_memory_access expects.
Also adds a PATTERN test (X=1..32) to exercise mixed even/odd byte reads
and catch this class of bug going forward.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WQV3vS9TXaGDJ5cRfnfidt