[SoundMatt]

Summary

Implements ROADMAP.md milestone 44, "Wire Format Core (v2.0.0)" — the first milestone of Phase 13's full TC18 protocol replacement.

• rcp/wire.hpp is entirely rebuilt as an IEEE 1722 AVTPDU/ACF codec:

  • NTSCF and TSCF AVTPDU headers (encode/decode, subtype validation)
  • ACF_ABB (0x0E, no timestamp) and ACF_GBB (0x0D, 64-bit message_timestamp) message framing
  • The shared byte_message_info fields: acf_msg_type, acf_msg_length, pad, mtv, byte_bus_id, evt (ack + 3-bit sub-opcode), hs, cs, transaction_num, op, rsp, err, ms, and the dual-purpose read_size/segment_num field
  • StreamId (MAC + locally-assigned suffix) and byte_bus_id addressing, with make_response() structurally enforcing the "echo byte_bus_id/transaction_num back unchanged" rule
  • The mandatory standard request kind and the four response semantic types (acknowledge / write / read / error)
  • avtp_timestamp/message_timestamp with an explicit fallback rule (effective_timestamp) that returns std::nullopt rather than defaulting to zero when neither timestamp source is valid
  • No dependency on rcp.hpp's Zone/Command/Controller/Registry model, and no transport assumption (works equally under Ethernet, IEEE1722-over-UDP/IP, or CAN)

• The old 16-byte frame codec that used to live in wire.hpp is preserved byte-for-byte under a new rcp/legacy_wire.hpp (namespace rcp::legacy_wire), since rcp/udp.hpp still depends on it and isn't rebuilt against real AVTPDU framing until v2.13.0. rcp/udp.hpp now includes legacy_wire.hpp instead, with an explanatory header comment.

• Test coverage: tests/test_wire.cpp is rewritten to cover the new codec (REQ-WIRE-001..014); the old 16-byte-frame tests move unchanged to tests/test_legacy_wire.cpp (REQ-UDP-001..012, still passing). .fusa-reqs.json gets the 14 new REQ-WIRE-* entries.

• Version bumped to 2.0.0 (CMakeLists.txt, version.hpp), README header table updated, ROADMAP.md milestone 44 marked done.

Per the roadmap's own framing, this is a pure wire-codec milestone — no lifecycle, discovery, or endpoint behavior is included, and full bit-for-bit conformance against other TC18 implementations isn't claimed until v2.6.0.

Test plan

• cmake --build clean on clang (macOS) and gcc — both Debug and Release
• ctest full suite: 42/42 tests passing (100%), including new rcp_wire and rcp_legacy_wire
• cpp-rcp version/capabilities CLI smoke check — reports 2.0.0 correctly
• No new compiler warnings introduced (checked against this repo's -Wall -Wextra -Wpedantic -Wshadow -Wold-style-cast -Wcast-align flag set)
• CI (clang-tidy/DCO/relay-conform/coverage matrix) — pending, see PR checks