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]>

tsconfig.json

@@ -18,7 +18,6 @@
 				"name": "next"
 			}
 		],
-		"baseUrl": ".",
 		"paths": {
 			"@/*": ["./src/*"]
 		}