feat: v2.15.0 — Application-Layer Protocol Bridge Rebind (§Phase 15 milestone 59)

[SoundMatt]

Summary

Implements ROADMAP.md milestone 59, "Application-Layer Protocol Bridge Rebind (v2.15.0)" — the first unchecked/undone milestone in the roadmap's own stated order (milestones 44–58, v2.0.0–v2.14.0, all carry a "Done" note; milestone 59 did not).

• Rebinds mqttbr.hpp, ddsbr.hpp, someipbr.hpp, restbridge.hpp, grpcbridge.hpp, udsbr.hpp, doipbr.hpp per the Satellite Package Disposition table's ADAPT entry for each file.
• Each pre-replacement <Name>Controller : public rcp::Controller wrapper (keyed by the removed Zone type) becomes a standalone <Name>Bridge class — the same "primitives, not a wrapped chokepoint" choice rcp/authz.hpp (v2.11.0) and rcp/tsn.hpp/rcp/record.hpp/rcp/observe.hpp (v2.14.0) already made, since there is no unified client-side send() chokepoint left to wrap.
• Addressing moves from Zone to the opaque per-connection stream_key plus avtp::ByteBusId endpoint pair every other Phase 14/15 header keys on since v2.10.0.
• Each bridge's send() becomes request(), shaped to match rcp/record.hpp's/rcp/observe.hpp's RequestFn — the same "new client-side send-equivalent call" shape as rcp/udp.hpp's Client::request core signature.
• The old subscribe()/StatusChannel method is dropped with no replacement (belonged to rcp::Controller's status-telemetry push model, no analog in the target spec).
• Every method still returns errc::function_not_supported (close() still succeeds) — no real MQTT/DDS/SOME-IP/REST/gRPC/UDS/DoIP behavior is implemented, exactly as this milestone's scope calls for; each protocol's Config struct is unchanged.
• canbr.hpp/linbr.hpp are untouched — out of scope for this milestone, separate DEPRECATE item at v2.17.0.
• version.hpp/CMakeLists.txt bumped to 2.15.0; ROADMAP.md gets a "Done (v2.15.0)" note.

Grepping the tree for consumers of each file's pre-v2.15.0 API beyond its own test found none, so no legacy-shim split file was needed, matching the v2.13.0/v2.14.0 rebuild convention. Tests entirely rewritten under the same file/prefix identity as the discarded pre-replacement coverage, traced in .fusa-reqs.json.

Test plan

• cmake -B build && cmake --build build --parallel — clean build
• ctest --test-dir build --output-on-failure -j1 — 60/60 tests passing
• relay conform --strict build/cpp-rcp (RELAY §12 conformance gate) — PASS
• cpfusa check — 0 errors
• cpfusa lint — 0 errors (from a clean checkout, no build/ dir noise)
• cpfusa cyber — 0 errors
• cpfusa trace --req-coverage 100 — passes at 100% requirement coverage