Shuffle Fix, Deck Animation, and Stability

Fixes

• Shuffle bias — the shuffle algorithm had a statistical bias that gave cards near the top of the deck a higher chance of staying there. Fixed with a correct Fisher-Yates implementation.
• Deck bounce animation — the bounce animation when cards are added to the deck was using the wrong position as its anchor, making it look wrong. Fixed.
• Card rotation mutation — moving cards between zones (graveyard, stacks) was accidentally mutating the parent mesh rotation, causing visual glitches. Fixed by cloning the quaternion before inverting.
• Transfer crash — transferring a card with a missing source zone could crash the game. Now handled gracefully.
• Animation path guard — added a guard against undefined points in card movement paths, preventing a class of rare animation crashes.