feat(study): use seeded PRNG for deterministic card shuffle order

Shuffle order is now fixed within a study day by seeding mulberry32
with the study day boundary timestamp (3:00 AM rollover).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 0 insertions, 14 deletions

diff --git a/src/client/utils/shuffle.ts b/src/client/utils/shuffle.ts
deleted file mode 100644
index a2b8fec..0000000
--- a/src/client/utils/shuffle.ts
+++ /dev/null
@@ -1,14 +0,0 @@
-/**
- * Fisher-Yates shuffle algorithm.
- * Returns a new shuffled array (does not mutate the original).
- */
-export function shuffle<T>(array: T[]): T[] {
-	const result = [...array];
-	for (let i = result.length - 1; i > 0; i--) {
-		const j = Math.floor(Math.random() * (i + 1));
-		const temp = result[i] as T;
-		result[i] = result[j] as T;
-		result[j] = temp;
-	}
-	return result;
-}