Rebuild atomcms-next foundation on Prisma (align to habbo-next reference)

Replace the superseded Drizzle monorepo scaffold with a single-app Prisma 7
data layer, mirroring the proven habbo-next approach to the shared Arcturus
emulator DB (introspect/conform only, idempotent SQL migrations via a custom
runner; never migrate-diff).

- prisma/schema.prisma: User, UsersCurrency (composite PK), Ban, WebsiteSetting
  mapped to AtomCMS's default.sql columns; client generated to src/generated/prisma
- src/lib/prisma.ts: PrismaMariaDb adapter singleton; src/env.ts zod env
- src/lib/services: siteSettings (cached setting() equivalent) + CurrencyType enum
- prisma/migrations + scripts/apply-migrations.ts: idempotent CMS-table runner

Verified: prisma generate OK, tsc --noEmit exit 0, vitest 6/6 pass.

src/lib/prisma.ts

@@ -0,0 +1,27 @@
+import { PrismaMariaDb } from "@prisma/adapter-mariadb";
+import { PrismaClient } from "@/generated/prisma/client";
+import { env } from "@/env";
+
+const globalForPrisma = globalThis as unknown as { prisma?: PrismaClient };
+
+function createPrismaClient(): PrismaClient {
+  const url = new URL(env.DATABASE_URL);
+  const adapter = new PrismaMariaDb({
+    host: url.hostname,
+    port: Number(url.port) || 3306,
+    user: decodeURIComponent(url.username),
+    password: decodeURIComponent(url.password),
+    database: url.pathname.replace(/^\//, ""),
+    connectionLimit: env.DATABASE_POOL_SIZE,
+    connectTimeout: 10_000,
+    idleTimeout: env.DATABASE_IDLE_TIMEOUT_MS,
+  });
+  return new PrismaClient({
+    adapter,
+    log: env.NODE_ENV === "development" ? ["error", "warn"] : ["error"],
+  });
+}
+
+export const prisma = globalForPrisma.prisma ?? createPrismaClient();
+
+if (env.NODE_ENV !== "production") globalForPrisma.prisma = prisma;