v0.1.0: Saving, audio slider and more

Thank you for over 3000 players!

Here is a hotfix that should remedy some of the most-pressing issues that were brought up.

Changes:

• Implemented save system
  • The game now automatically saves when being closed (desktop-only), every 30 seconds and when you buy an upgrade. Sorry for anyone that unexpectedly lost their progress

• Increased the hitbox area of coins
  • Coins are now easier to hit and don't need high-level accuracy sniper training in order to be triggered

• Added an audio slider so you can reduce the coin flip sound effect
  • Tell your ears we're sorry!

• Changed the gold coin description to correctly show the amount it gains when flipped

• Migrated to Godot 4.4