Add CM1 and CM2 boards, six backdrops and a quit button (0.8.0)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

assets/environments/jungle_backdrop.svg.import

@@ -0,0 +1,43 @@
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+}
+
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+dest_files=["res://.godot/imported/jungle_backdrop.svg-5c35e665b8afebdb8495150498a52935.ctex"]
+
+[params]
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