[cpp-RCP-FS-03] legacy_mock/redundancy/faultinject/config are live compiled consumers of the retired model #86

Location: include/rcp/legacy_mock.hpp:99,204; include/rcp/redundancy.hpp:37; include/rcp/faultinject.hpp:49; include/rcp/config.hpp:42,65-70,122; all four are built and tested per tests/CMakeLists.txt.

Finding: Four headers are still live, compiled, and tested consumers of the retired Zone/Controller/Registry model: legacy_mock.hpp defines a Controller/Registry pair implementing the old interfaces; redundancy.hpp defines a RedundantController implementing rcp::Controller; faultinject.hpp defines a fault-injecting Controller returning the old ResponseStatus::Error; and config.hpp defines a ZoneManifestEntry type that maps zone names like "FrontLeft" to Zone::FrontLeft and constructs a legacy_mock::Controller from it. Since all four are part of the test suite, the retired model isn't just present in the tree — it's actively exercised and kept "working" by CI, which makes it harder to remove and reinforces its apparent legitimacy as a supported surface.

Recommendation: Rebind config.hpp onto the TC18 register-map/endpoint model (this is the one with an actual reason to exist — zone-manifest-driven configuration — so it should move first), then delete legacy_mock.hpp outright, and re-express whatever redundancy.hpp/faultinject.hpp need in terms of relay::Caller/AcfMessageInfo instead of the retired Controller interface.

Verification: Independently re-read all four headers and tests/CMakeLists.txt against current HEAD (commit 4b9449a, 2026-07-29). Confirmed each still defines/derives from the retired types as described, and confirmed all four are registered as built test targets.

Filed from the 2026-07-29 ecosystem audit register; independently re-verified against current HEAD before filing.