fix(pay-card): declare the webp module for the card flow typecheck

The auth leaf now imports a `*.webp` hero. `@features/flow-pay-card` compiles
that source across the package boundary, and an ambient declaration does not
cross a workspace boundary, so `tsc` could not resolve the import.

Re-declare the module in this package, as it already does for `*.svg`. Both
apps carry their own declaration, so only this flow package was exposed.

Author: liviuciulinaru

features/flow/pay-card/src/assets.d.ts

@@ -6,3 +6,10 @@ declare module "*.svg" {
   const src: string;
   export default src;
 }
+
+// The auth leaf imports its `*.webp` hero the same way, and this package compiles that source
+// across the package boundary too — mirroring `features/flow/pay-card-auth/src/assets.d.ts`.
+declare module "*.webp" {
+  const src: string;
+  export default src;
+}