fix(companies): clear currency filter on reset all

Reset currency to an empty string instead of undefined so React Hook Form
overwrites the stored value and the controlled currency Select clears.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/Tables/companies/useCompanyListPresenter.ts

@@ -104,7 +104,7 @@ export const useCompanyListPresenter = () => {
       name: "",
       email: "",
       phone: "",
-      currency: undefined,
+      currency: "",
       employee_count: "",
     });
     router.push(pathName);