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/actions/users.ts

@@ -2,7 +2,6 @@
 
 import crypto from "node:crypto";
 import { z } from "zod";
-import { Prisma } from "@/generated/prisma/client";
 import { hashPassword } from "@/lib/auth/password";
 import { PERMS } from "@/lib/permissions";
 import { prisma } from "@/lib/prisma";
@@ -81,10 +80,14 @@ export const createUser = adminAction(
 			return actionOk({ id: user.id, username: user.username });
 		} catch (err) {
 			if (
-				err instanceof Prisma.PrismaClientKnownRequestError &&
+				err &&
+				typeof err === "object" &&
+				"code" in err &&
 				err.code === "P2002"
 			) {
-				const target = (err.meta?.target as string[]) ?? [];
+				const target = (
+					(err as { meta?: { target?: string[] } }).meta?.target as string[]
+				) ?? [];
 				if (target.includes("username"))
 					throw new ActionError("Username already taken");
 				if (target.includes("mail"))