Add protocol-certification M0 catalog, loader, and empty report (2.64.0).

Versioned JSON skeletons without invented ohms/mm/ps. RECOMMENDED is not
FAIL-mandatory; typical-as-standard is rejected. Report Protocolli is empty
until recognition (M1+). Native src overlays inherited periscopex on the
package path.

backend/__init__.py

@@ -10,9 +10,29 @@ from pathlib import Path
 from pkgutil import extend_path
 
 _REPO = Path(__file__).resolve().parents[1]
-for _p in (_REPO / "periscope" / "src", _REPO / "periscope" / "dependency"):
+_SRC = _REPO / "periscope" / "src"
+_DEP = _REPO / "periscope" / "dependency"
+# Last insert is searched first: native src overlays inherited dependency.
+for _p in (_DEP, _SRC):
     _s = str(_p)
-    if _p.is_dir() and _s not in sys.path:
-        sys.path.insert(0, _s)
+    if not _p.is_dir():
+        continue
+    if _s in sys.path:
+        sys.path.remove(_s)
+    sys.path.insert(0, _s)
 
-__path__ = list(extend_path(__path__, __name__))
+
+def _prefer_native_backend(paths: list[str]) -> list[str]:
+    src, other, dep = [], [], []
+    for p in paths:
+        norm = p.replace("\\", "/")
+        if "/periscope/src/" in norm:
+            src.append(p)
+        elif "/periscope/dependency/" in norm:
+            dep.append(p)
+        else:
+            other.append(p)
+    return src + other + dep
+
+
+__path__ = _prefer_native_backend(list(extend_path(__path__, __name__)))