Adds in-game debug menu addon

Adds an in-game debug menu that displays performance metrics (FPS, frame times) and hardware/software information.

The menu can be toggled using the F3 key (or a custom input binding). It has different display styles, ranging from a compact FPS display to a detailed view with graphs and system information.

assets/sprites/enemies/slimes_blue.png.import

@@ -0,0 +1,34 @@
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