roundtrip.py converts the radare2 disassembly (qunexus_v2.2.1.asm) into a
single sdas8051 assembler source (firmware.asm) and verifies it re-assembles
byte-identical to the 54,279-byte stock image (base 0x2400).
31,051 of 31,346 items (99.06%) re-assemble from mnemonics; 295 are
pinned to .db where r2's display syntax doesn't round-trip through
sdas8051 (256 ajmp/acall that sdas8051 mis-encodes, 39 data-in-code).
Converges in 3 iterations.
Also adds patch_usb1_to_cv.asm (the USB-1->CV patch as a standalone
sdas8051 source) and verify_patch_asm.py (proves the assembled patch
matches the bytes written to the device over C2).
Reproduce: python3 roundtrip.py
