Add endpoint to create allowance (#34)

Closes #11

Reviewed-on: #34

backend/dto.go

@@ -5,11 +5,21 @@ type User struct {
 	Name string `json:"name"`
 }
 
+type UserWithAllowance struct {
+	ID        int    `json:"id"`
+	Name      string `json:"name"`
+	Allowance int    `json:"allowance"`
+}
+
 type Allowance struct {
 	Allowance int    `json:"allowance"`
 	Goals     []Goal `json:"goals"`
 }
 
+type PostAllowance struct {
+	Allowance int `json:"allowance"`
+}
+
 // Task represents a task in the system.
 type Task struct {
 	ID       int    `json:"id"`