The v1-era tb_cross_layer_ft2232h.v cosim TB no longer matches
production after the protocol-v2 / opcode dispatch rework (PR-G).
Equivalent v2 coverage now lives in the FPGA regression's
tb_usb_protocol_v2.v and tb_system_opcodes.v.
Removed:
- tb_cross_layer_ft2232h.v (716 lines)
- Tier 2 (Verilog cosimulation) from test_cross_layer_contract.py
- iverilog/vvp tool detection and CI install step in ci-tests.yml
Tier 1 (static parser) and Tier 3 (C stub execution) remain. CI
no longer needs apt-get install iverilog.
contract_parser.py updated to reflect the slimmer two-tier model.