refactor: replace Prisma ORM runtime with Drizzle ORM facade

- Replace Prisma client runtime with Drizzle ORM (zero Prisma engine/query engine in production)
- Add Prisma-compatible facade (@/lib/prisma-facade.ts) backed by Drizzle for backwards compatibility
- Runtime queries route through Drizzle ORM; @prisma/client is now devDependency (types only)
- Remove @prisma/adapter-mariadb dependency; delete prisma-pool.ts and types/prisma.ts
- New Drizzle schema layer: src/db/schema.ts (176 tables) and src/lib/db.ts (connection)
- Update README documenting the dual-layer ORM architecture
- Restore src/generated/ gitignore (build artifact for local type generation)
- 0 TypeScript errors, 583 tests passing

The facade intentionally uses `any` types to match the Prisma Client API surface,
allowing existing code to run unmodified while routing queries through Drizzle at runtime.

drizzle.config.ts

@@ -0,0 +1,16 @@
+import "dotenv/config";
+import { defineConfig } from "drizzle-kit";
+
+// The schema is generated by scripts/generate-drizzle-schema.mjs from
+// prisma/schema.prisma + live DB introspection. This DB is shared live with the
+// Arcturus emulator, so we NEVER run `drizzle-kit migrate`/`push` against it —
+// CMS-only schema changes stay in prisma/migrations/*.sql via `pnpm db:migrate`.
+export default defineConfig({
+	dialect: "mysql",
+	schema: "./src/db/schema.ts",
+	dbCredentials: {
+		url: process.env.DATABASE_URL ?? "",
+	},
+	strict: true,
+	verbose: true,
+});