migration: prove standalone maintenance and correct visual evidence

app/tools/build_architecture_inventory.py

@@ -75,6 +75,14 @@ def css_layers(html: str) -> list[str]:
     return re.findall(r'<link[^>]+rel="stylesheet"[^>]+href="([^"]+)"', html)
 
 
+def source_metrics(path: Path) -> dict[str, int]:
+    text = path.read_text(encoding="utf-8")
+    return {
+        "bytes": len(text.encode("utf-8")),
+        "lines": len(text.splitlines()),
+    }
+
+
 def code_hotspots() -> list[dict[str, Any]]:
     candidates = [
         "backend/application.py",
@@ -99,13 +107,7 @@ def code_hotspots() -> list[dict[str, Any]]:
         path = ROOT / name
         if not path.is_file():
             continue
-        rows.append(
-            {
-                "path": name,
-                "bytes": path.stat().st_size,
-                "lines": len(path.read_text(encoding="utf-8").splitlines()),
-            }
-        )
+        rows.append({"path": name, **source_metrics(path)})
     return sorted(rows, key=lambda item: item["bytes"], reverse=True)