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]>

scripts/migration-idempotency.test.ts

@@ -5,7 +5,7 @@ import { describe, expect, it } from "vitest";
 describe("radio columns migration", () => {
 	it("adds every column idempotently for partially migrated databases", () => {
 		const sql = readFileSync(
-			resolve("prisma/migrations/0009_radio_contests_giveaways_columns.sql"),
+			resolve("drizzle/migrations/0009_radio_contests_giveaways_columns.sql"),
 			"utf8",
 		);
 		const additions = sql.match(/ADD COLUMN(?! IF NOT EXISTS)/gi) ?? [];