feat: complete dotnet formula and platform cutover gates

tools/validate_platform_transition_wbs_v1.py

@@ -290,6 +290,16 @@ def _check_p5() -> dict[str, Any]:
 
 
 def main() -> int:
+    # The historical P1-P4 checks described the retired Python/SQLite/XLSX
+    # runtime. Platform transition now uses the .NET/PostgreSQL/JSON contract;
+    # keep this entry point for CI compatibility while delegating authority to
+    # the current cutover validator.
+    from tools.validate_dotnet_postgresql_json_cutover_v1 import main as validate_cutover
+
+    return validate_cutover()
+
+
+def _legacy_main() -> int:
     spec = _load_spec()
     phase = spec.get("phase_5_platform_transition") or {}
     roadmap_text = _read_text(ROADMAP_DOC_PATH)