E1S9.2: Rewrite the Elyssa cutscene so she fades in with visual effects

This makes it so Elyssa is manually faded into the scene while the event
flag-based fog and a new energy heart aura halo that wasn't there before
are gradually faded out simultaneously.

There is a minor glitch where the aura halo appears to become brighter
for a moment at the beginning -- demands further investigation.