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Replace the superseded Drizzle monorepo scaffold with a single-app Prisma 7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/services/site-settings.ts

@@ -0,0 +1,39 @@
+import { prisma } from "@/lib/prisma";
+
+/**
+ * DB-driven CMS config, mirroring AtomCMS's `setting()` / habbo-next's
+ * `siteSettings`. Loads the whole website_settings table into a key→value map,
+ * cached in-process. Booleans are stored as the strings '1' / '0'.
+ */
+class SiteSettings {
+  private cache: Map<string, string> | null = null;
+
+  private async load(): Promise<Map<string, string>> {
+    if (this.cache === null) {
+      const rows = await prisma.websiteSetting.findMany({
+        select: { key: true, value: true },
+      });
+      this.cache = new Map(rows.map((r) => [r.key, r.value]));
+    }
+    return this.cache;
+  }
+
+  async get(key: string, fallback: string | null = null): Promise<string | null> {
+    const map = await this.load();
+    return map.has(key) ? (map.get(key) as string) : fallback;
+  }
+
+  async getBool(key: string, fallback = false): Promise<boolean> {
+    const map = await this.load();
+    if (!map.has(key)) return fallback;
+    const v = (map.get(key) as string).toLowerCase();
+    return v === "1" || v === "true";
+  }
+
+  /** Invalidate the in-process cache after a settings write. */
+  reload(): void {
+    this.cache = null;
+  }
+}
+
+export const siteSettings = new SiteSettings();