chore: set default output format to JPG, add .gitignore

- config.ini: output_format = jpg (quality 95)
- .gitignore: exclude build/, output/, IDE files

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,15 @@
+# Build
+build/
+
+# Output images
+output/
+
+# IDE
+.vscode/
+.idea/
+*.user
+
+# Compiled
+*.o
+*.a
+*.so

config.ini

@@ -28,7 +28,7 @@ film_type        = auto
 #   png8   – 8-bit PNG   (lossless, smaller files)
 #   tiff16 – 16-bit TIFF (lossless, for professional editing)
 #   jpg    – 8-bit JPEG  (lossy, smallest files)
-output_format    = png16
+output_format    = jpg
 
 # Output bit depth (8 or 16); ignored when format is jpeg
 output_bit_depth = 16