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.

src/lib/db.ts

@@ -0,0 +1,62 @@
+import { drizzle, type MySql2Database } from "drizzle-orm/mysql2";
+import mysql from "mysql2/promise";
+import * as relations from "@/db/relations";
+import * as schema from "@/db/schema";
+import { env } from "@/env";
+import { resolveConnectionLimit } from "@/lib/db-pool";
+
+const fullSchema = { ...schema, ...relations };
+
+const globalForDb = globalThis as unknown as {
+	db?: MySql2Database<typeof fullSchema>;
+};
+
+function createDb(): MySql2Database<typeof fullSchema> {
+	const url = new URL(env.DATABASE_URL);
+	const isBuild =
+		process.env.NEXT_PHASE === "phase-production-build" ||
+		process.env.NEXT_PHASE === "phase-production-compile";
+	const connectionLimit = resolveConnectionLimit(env.DATABASE_POOL_SIZE);
+	// Fail fast during SSG so Next can retry/fallback instead of hanging 30s+.
+	const connectTimeout = isBuild
+		? Math.min(env.DATABASE_CONNECT_TIMEOUT_MS, 5_000)
+		: env.DATABASE_CONNECT_TIMEOUT_MS;
+
+	const pool = mysql.createPool({
+		host: url.hostname,
+		port: Number(url.port) || 3306,
+		user: decodeURIComponent(url.username),
+		password: decodeURIComponent(url.password),
+		database: url.pathname.replace(/^\//, ""),
+		charset: "utf8mb4",
+		waitForConnections: true,
+		connectionLimit,
+		queueLimit: 0,
+		connectTimeout,
+		idleTimeout: env.DATABASE_IDLE_TIMEOUT_MS,
+		// Keep BIGINT precision; safe values come back as numbers, huge ones as
+		// strings (drizzle bigint mode maps both to JS bigint).
+		supportBigNumbers: true,
+	});
+
+	return drizzle(pool, {
+		schema: fullSchema,
+		mode: "default",
+		logger:
+			env.NODE_ENV === "development"
+				? {
+						logQuery(query, params) {
+							console.log("[db]", query, params);
+						},
+					}
+				: false,
+	});
+}
+
+export const db = globalForDb.db ?? createDb();
+
+if (env.NODE_ENV !== "production") globalForDb.db = db;
+
+export type Db = MySql2Database<typeof fullSchema>;
+
+export * from "@/db/schema";