feat: v2.14.0 — Auxiliary Transport & Cross-Cutting Rebind (§Phase 15 milestone 58)

[SoundMatt]

Summary

Implements ROADMAP.md milestone 58, "Auxiliary Transport & Cross-Cutting Rebind (v2.14.0)" — the seven ADAPT-category satellite packages the Satellite Package Disposition table lists, rebound onto the post-replacement stream/byte_bus_id addressing model:

• rcp/mdns.hpp — rescoped to host:port discovery for the UDP/IP transport variant specifically (ZoneInfo → ServerInfo, keyed by an opaque stream_key). TC18's own wire-level discovery (rcp/discovery.hpp, v2.2.0) needs no name service at all.
• rcp/tls.hpp — rebuilt as SecureClient/SecureServer wrapping rcp/udp.hpp's Server/Client (v2.13.0), same OpenSSL-gated-backend/stub split as before; now states plainly that the specification's preferred link-security mechanism is MACsec (802.1AE) at layer 2, which this package does not address.
• rcp/tsn.hpp — PCPMap now maps rcp::request::RequestCategory's seven-way execution-priority ordering (v2.5.0) instead of the removed Priority enum, via a standalone apply_priority() free function rather than a wrapped Controller (no unified client-side send() chokepoint exists yet — that lands at v2.16.0).
• rcp/shmem.hpp — ZoneServer/Controller become Channel/Registry, keyed by stream_key the same way rcp/watchdog.hpp's Manager already is.
• rcp/loan.hpp — loan::Controller becomes a standalone BufferPool (buffers re-zeroed on reuse), same "primitive, not a wrapped chokepoint" choice tsn.hpp makes here.
• rcp/record.hpp — wraps a RequestFn shaped like udp::Client::request's core signature; Entry now carries AcfMessageInfo/payload pairs, and a new read_binary makes the on-disk format round-trip losslessly (previously only asserted non-empty).
• rcp/observe.hpp — wraps the same RequestFn; Span/Metric swap Zone/CommandType for byte_bus_id/acf_msg_type/stream_key.

No other file in the tree depended on any of the seven pre-v2.14.0 APIs beyond their own tests, so no legacy-shim split file was needed anywhere (verified by grep before starting).

tests/test_{mdns,tls,tsn,shmem,loan,record,observe}.cpp are entirely rewritten under their existing REQ-*-NNN prefixes, traced in .fusa-reqs.json. version.hpp/CMakeLists.txt bumped to 2.14.0; README.md's header table and ROADMAP.md updated with a **Done (v2.14.0):** note.

Test plan

• cmake --build full project on C++17 and C++20 — clean
• ctest — 60/60 tests passing
• cpfusa check / lint / cyber — 0 errors
• cpfusa trace --req-coverage 100 — 480/480 requirements annotated + tested (100%)
• cpfusa verify — evidence bundle generated, 60/60 tests
• relay conform --strict against the built cpp-rcp CLI — PASS
• CI (GitHub Actions) — pending, to be polled after this PR opens