9a7eb54801
Factors the EXI_J4 pad merge out of synth.py so the synthesis path and the test exercise the same code. Verifies the device ID (04 02 02 00) enumerates over SP1 with J4 idle, over J4 with SP1 idle, and over SP1 again afterwards, plus a register read via J4 and the full cs_n truth table. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>