fix: resolve TypeScript compilation errors from service extraction

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/schemas/common.ts

@@ -1,11 +1,11 @@
-import { ZodSchema, ZodError } from 'zod';
+import { ZodSchema, z } from 'zod';
 
 export function parseBody<T>(schema: ZodSchema<T>, body: unknown): { data: T } | { error: string } {
   try {
     return { data: schema.parse(body) };
   } catch (e) {
-    if (e instanceof ZodError) {
-      return { error: e.errors.map(err => err.message).join(', ') };
+    if (e instanceof z.ZodError) {
+      return { error: e.issues.map((err: z.ZodIssue) => err.message).join(', ') };
     }
     return { error: 'Neplatný požadavek' };
   }