v0.9.21 - Challenge Mode Fixes

Fix: Boss Rush full clear now returns you to where you left off — completing all 40 floors no longer strands you at Area 40 with unkillable enemies.

Fix: Energy bar auto-fire no longer refreshes a skill that is already active (Cat Frenzy, Rally, Gold Rush).

Fix: Boss Rush boss kills no longer inflate the stardust reward when you prestige.

Fix: Rune Golem in Area 23 (Ancient Library) no longer appears as a plain square.

Fix: Mission Complete popup no longer briefly flickers as a double banner when claiming a daily goal.