macos-native: clean branch for cloning and building the Tauri desktop app

Orphan branch with no history — includes the Tauri shell (src-tauri/) and
vendored Three.js (vendor/) that were never pushed before, so a fresh clone
can actually build the native app. Drops the large .pcd sample captures and
editor cruft (.obsidian, .DS_Store); they aren't needed to build or run the
app (point clouds load via drag-and-drop, not bundling).

.gitignore

@@ -0,0 +1,10 @@
+# Point cloud captures — not needed to build/run the app (drag-and-drop loads them)
+*.pcd
+
+# OS / editor cruft
+.DS_Store
+.obsidian/
+
+# Rust build output and the staged web copy (regenerated by stage-web.sh)
+/src-tauri/target/
+/src-tauri/web/