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/components/public/radio-player.tsx

@@ -10,7 +10,7 @@ import { useEventSource } from "@/lib/use-event-source";
  * radio via a hidden <audio> element, with play/pause, a volume slider, the
  * current DJ / now-playing text, and a live listener count.
  *
- * It is a CLIENT component and must NOT import prisma / siteSettings.
+ * It is a CLIENT component and must NOT import db / siteSettings.
  * Config is fetched once on mount; now-playing + listeners come via SSE
  * (/api/radio/stream) for real-time updates.
  *