UI: Change UI layout

added character 2D assets.
added 2 more bar for two characters
change UI layout to simple black
remove unnecessary space in UI
task for elmer
pag palit palitan mo yung character image kung sino yung leader dapat
siya yung nasa malaki then nasa taas niya yung susunod pag nagchange
character tapos yung health, mana at exp nagbabago rin pati rin yung
skill icons
Enemy Particles: Death particle