Add bevy_egui and use example code from there, use mold for starter Rust linking and update README

Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+bevy_egui = "0.38.1"
 cpal = "0.17.0"
 rand = "0.9.2"
 rfd = "0.16.0"
@@ -17,5 +18,6 @@ features = [
   "bevy_winit",
 ]
 
-[profile.dev.package."*"]
-opt-level = 3
+[target.'cfg(target_os = "linux")']
+linker = "clang"
+rustflags = ["-C", "link-arg=-fuse-ld=/usr/bin/mold"]