Add .gitignore (per-frame PNGs and resume markers stay local)

.gitignore

@@ -0,0 +1,13 @@
+.cache/
+__pycache__/
+*.pyc
+.DS_Store
+
+# glb_render/ ships ONLY the four per-view MP4s and their camera JSONs.
+# Everything else there is local working state — the ~2.9M per-frame PNGs the
+# MP4s were composed from, and the renderer's .rendered/ resume markers.
+glb_render/**
+!glb_render/*/
+!glb_render/*/v[0-9][0-9][0-9].mp4
+!glb_render/*/v[0-9][0-9][0-9].json
+glb_render/.rendered/