chore(db): finish Prisma cutover to Drizzle Kit tooling

Move CMS SQL to drizzle/migrations, drop prisma packages/schema, wire drizzle-kit scripts, and regenerate schema names from src/db/schema.ts.

Co-authored-by: Cursor <[email protected]>

src/app/(site)/leaderboard/page.tsx

@@ -10,7 +10,7 @@ export const revalidate = 300;
 
 export const metadata = { title: "Leaderboard" };
 
-// Currency type ids (see prisma/schema.prisma UsersCurrency):
+// Currency type ids (see UsersCurrency in src/db/schema.ts):
 //   Credits = -1 (lives on users.credits), Duckets = 0, Diamonds = 5.
 const TABS = [
 	{ key: "credits", label: "Credits", coin: "credits" },