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

backend/contracts/sendico/models/auth/token_data.yaml

@@ -0,0 +1,17 @@
+components:
+  schemas:
+    TokenData:
+      description: Authentication token payload with expiration metadata.
+      type: object
+      additionalProperties: false
+      required:
+        - token
+        - expiration
+      properties:
+        token:
+          description: Issued authentication token value.
+          type: string
+        expiration:
+          description: RFC 3339 timestamp when the token expires.
+          type: string
+          format: date-time