P4 (PARKED, Elazar) solo-mars as default alert/eventLog responder — gated on fine-tuning + backtest pass (bs-mr8o7w73qz4)

PARKED by Elazar 2026-07-06: fine-tune solo first, revisit later, not now. Solo becoming the default responder for app/appEvents/eventLog alerts requires (1) P2 triage playbook codified into solo-mars-cc.md (MARS-403), (2) P3 backtest of past alerts passing with ZERO missed-reals + benign-precision >=90%, (3) Elazar's explicit solo-scoped re-enable of fly-solo (currently DISABLED fleet-wide, project_flysolo_disabled). Nothing auto-flips; no work runs on this until Elazar gives go. Evidence packet for the go = per-project backtest pass-rate table.