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/lib/safe-action-shared.ts

@@ -1,4 +1,4 @@
-import { ZodError } from "zod";
+import { ZodError, z } from "zod";
 import { handleActionError as foundationHandle } from "@/lib/foundation/action";
 
 export type ActionResult<T = Record<string, unknown>> =
@@ -27,7 +27,7 @@ export function handleActionError(error: unknown): ActionResult<never> {
 		return {
 			ok: false,
 			error: "Validation failed",
-			fieldErrors: error.flatten().fieldErrors as Record<string, string[]>,
+			fieldErrors: z.flattenError(error).fieldErrors as Record<string, string[]>,
 		};
 	}
 	if (error instanceof Error && error.name === "ActionError") {