Add Redis caching methods for customer-user mappings

- Introduced methods `cache_customer_number_from_user_id`, `get_customer_number_from_user_id`, and `clear_customer_number_from_user_id` to the `Redis` class.
- Updated the `Redis_i` interface to define these new methods.
- Enhances customer-user mapping logic by integrating Redis for efficient caching and retrieval.

services/nginx/app/classes/redis.php

@@ -380,6 +380,35 @@ class redis implements redis_i
         return $this;
     }
 
+    /**
+     * @inheritDoc
+     */
+    public function cache_customer_number_from_user_id(int $user_id, int $customer_number): self
+    {
+        // Cache the customer number from user id
+        $this->set('customer_number_from_user_id_' . $user_id, $customer_number);
+        return $this;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function get_customer_number_from_user_id(int $user_id): int|null
+    {
+        // Get the customer number from user id
+        return $this->get('customer_number_from_user_id_' . $user_id);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function clear_customer_number_from_user_id(int $user_id): self
+    {
+        // Clear the customer number from user id
+        $this->delete('customer_number_from_user_id_' . $user_id);
+        return $this;
+    }
+
     public function expire(string $key, int $seconds): self
     {
         // Set the expiration time for a key

services/nginx/app/interfaces/redis_i.php

@@ -244,4 +244,26 @@ interface redis_i
      * @return self
      */
     public function clear_user_id_from_customer_number(int $customer_number): self;
+
+    /**
+     * Get a customer number from user id from the cache
+     * @param int $user_id
+     * @return int|null
+     */
+    public function get_customer_number_from_user_id(int $user_id): int|null;
+
+    /**
+     * Cache a customer number from user id
+     * @param int $user_id
+     * @param int $customer_number
+     * @return self
+     */
+    public function cache_customer_number_from_user_id(int $user_id, int $customer_number): self;
+
+    /**
+     * Clear a customer number from user id from the cache
+     * @param int $user_id
+     * @return self
+     */
+    public function clear_customer_number_from_user_id(int $user_id): self;
 }