refactor(backend): Redis -> Memcached

backend/package.json

@@ -37,8 +37,8 @@
         "jwks-rsa": "^3.1.0",
         "loki-logger-ts": "^1.0.2",
         "marked": "^15.0.7",
+        "memjs": "^1.3.2",
         "nanoid": "^5.1.5",
-        "redis": "^5.0.1",
         "response-time": "^2.3.3",
         "swagger-ui-express": "^5.0.1",
         "uuid": "^11.1.0",
@@ -50,6 +50,7 @@
         "@types/cors": "^2.8.17",
         "@types/express": "^5.0.0",
         "@types/js-yaml": "^4.0.9",
+        "@types/memjs": "^1.3.3",
         "@types/node": "^22.13.4",
         "@types/response-time": "^2.3.8",
         "@types/swagger-ui-express": "^4.1.8",