Modernize retained Linux WebGL CMake baselines

scripts/dev/check_retained_platform_cmake.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+"""Guard retained non-root platform CMake files during Phase 6 migration."""
+
+from __future__ import annotations
+
+import json
+import re
+import sys
+from pathlib import Path
+
+
+RETAINED_PLATFORM_CMAKE = [
+    Path("linux/CMakeLists.txt"),
+    Path("webgl/CMakeLists.txt"),
+]
+
+
+def repo_root() -> Path:
+    return Path(__file__).resolve().parents[2]
+
+
+def cmake_minimum_version(text: str) -> tuple[int, ...] | None:
+    match = re.search(r"cmake_minimum_required\s*\(\s*VERSION\s+([0-9.]+)", text, re.I)
+    if not match:
+        return None
+    return tuple(int(part) for part in match.group(1).split("."))
+
+
+def main() -> int:
+    root = repo_root()
+    results: dict[str, object] = {}
+    ok = True
+
+    for path in RETAINED_PLATFORM_CMAKE:
+        text = (root / path).read_text(encoding="utf-8")
+        minimum_version = cmake_minimum_version(text)
+        has_target_cxx23 = "target_compile_features(panopainter PRIVATE cxx_std_23)" in text
+        has_cxx_extensions_off = "CXX_EXTENSIONS OFF" in text
+        uses_global_cxx_standard_flag = bool(re.search(r"-std=c\+\+14|-std=c\+\+17|-std=c\+\+20", text))
+        platform_ok = (
+            minimum_version is not None
+            and minimum_version >= (3, 10)
+            and has_target_cxx23
+            and has_cxx_extensions_off
+            and not uses_global_cxx_standard_flag
+        )
+        ok = ok and platform_ok
+        results[str(path)] = {
+            "ok": platform_ok,
+            "minimumVersion": ".".join(str(part) for part in minimum_version) if minimum_version else None,
+            "hasTargetCxx23": has_target_cxx23,
+            "hasCxxExtensionsOff": has_cxx_extensions_off,
+            "usesGlobalCxxStandardFlag": uses_global_cxx_standard_flag,
+        }
+
+    print(json.dumps({"ok": ok, "platforms": results}, separators=(",", ":")))
+    return 0 if ok else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())