chore: upgrade Zod 4, Vitest 4, and TypeScript 7

Bump major tooling stacks and adapt Zod error APIs (issues/flattenError) plus tsconfig paths for TS 7 baseUrl removal.

Co-authored-by: Cursor <[email protected]>

src/actions/register.ts

@@ -54,7 +54,7 @@ export async function register(
 
 	const parsed = registerSchema.safeParse(raw);
 	if (!parsed.success) {
-		return parsed.error.errors[0]?.message ?? "Invalid input";
+		return parsed.error.issues[0]?.message ?? "Invalid input";
 	}
 
 	const { username, mail, password, look } = parsed.data;