Balance patch to adjust general difficulty and some minor fixes

Difficulty tweaks

• Increase invuln frame time (change from 0.5s to 1s)
• Increase spawn rate of hearts (from 25s to 20s)
• Decrease spawn rate of wasps and mega flies and bomb flies (from 3s, 5s, 5s to 5s, 6s, 6s)
• Increase rate of surge buildup (from 5 (20) to 6.25 (16)

QoL

• Added a wait on click to end screen to restart instead of timer

Bug fixes

• Can no longer trigger both endings if player dies at the same time as final boss
• Fixed ending screen showing up behind sprites
• Fixed boss death animation not playing if killed by the electric surge power