perf(mesher): shared proof-driven sampling skips certified-uniform blocks (L52); FI 7.1 -> 5.6 s; R21

The shared marching-cubes mesher applies its 8-cell block proofs at step 2 for standalone shape contexts
and skips density-grid fills outside certified-uniform blocks (plus a one-sample normal halo); mixed and
unknown blocks still sample exactly. FI certified-air boxes 1,959 -> 14,119; FI LOD1 samples -63%. FI whole
view 7.08 -> 5.61 s (-21%), moving p50 about -33%; SW unchanged. Geometry hashes identical (no version
bump); proof audit 36.9 M samples, 0 violations, Clang and GCC. Source stamp now covers the standalone
mesher copy. Research R21 (deepened): native Core cave generator design.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Tools/verify/source_stamp.py

@@ -24,6 +24,12 @@ def manifest_entries(root: Path, include_unreal: bool = False) -> list[tuple[str
     for suffix in ("*.h", "*.hpp", "*.cpp"):
         files.update(source.glob(suffix))
 
+    # The standalone BuildLinux wrapper compiles the plugin mesher sources from this tree.
+    # Include their contents, not only the generated wrapper paths, in the executable stamp.
+    standalone_plugin_source = source / "VoxelForge"
+    for suffix in ("*.h", "*.hpp", "*.cpp", "*.inl"):
+        files.update(standalone_plugin_source.rglob(suffix))
+
     for path in standalone.glob("Build*"):
         if path.is_file():
             files.add(path)