docs: add .gitignore for binary assets and output files

.gitignore

@@ -1,4 +1,4 @@
-# --- Binary input assets ---
+# --- Binary input assets (per README guideline) ---
 # Audio
 *.mp3
 *.wav
@@ -16,6 +16,7 @@
 *.webp
 *.svg
 *.bmp
+*.ico
 
 # Fonts
 *.ttf
@@ -31,9 +32,21 @@
 *.webm
 
 # --- Video output ---
-# (same extensions, intentionally duplicated for clarity)
 *.mp4
 *.mov
 *.avi
 *.mkv
 *.webm
+
+# --- Remotion / Node.js ---
+node_modules/
+out/
+dist/
+remotion-studio/
+
+# --- OS / IDE ---
+.DS_Store
+Thumbs.db
+*.swp
+*.swo
+*~