Sonic the Hedgehog 2 v0.9.13

Restore Knuckles' original collision-box transitions, wall/climb probes, terrain recovery and boss rebound. Custom characters now follow native palette-fade timing and scanline water boundaries. Act-clear screens use the selected character's name, and Knuckles uses his original monitor and continue-award artwork. Native HUD and title-card lettering correctly covers character overlays, including character-specific competition HUDs.

Special stages use native Sonic/Tails roles. Existing in-game saves and settings are preserved; save states remain specific to the build.

QA: @TheGabeMaster29.