Bootstrap copied BFF and local accounts with public Sendico contracts (#34)

backend/contracts/sendico/api/callbacks/response/callback.yaml

@@ -0,0 +1,22 @@
+components:
+  schemas:
+    CallbacksAuthData:
+      description: Authenticated response payload containing callback configurations.
+      type: object
+      additionalProperties: false
+      required:
+        - accessToken
+        - callbacks
+      properties:
+        accessToken:
+          description: Refreshed access token to be used in subsequent API calls.
+          $ref: ../../../models/auth/token_data.yaml#/components/schemas/TokenData
+        callbacks:
+          description: Collection of callbacks configured for the authenticated scope. JWS-signed callbacks expose read-only verification JWKs via `callbacks[].signingKeys`.
+          type: array
+          items:
+            $ref: ../../../models/callback/callback.yaml#/components/schemas/Callback
+        generatedSigningSecret:
+          description: Newly generated signing secret when HMAC signing material is created or rotated. JWS-signed callbacks do not populate this field.
+          type: string
+          nullable: true