Add RAG client

src/main/java/com/example/service/base/IntentDetectionService.java

@@ -0,0 +1,24 @@
+package com.example.service.base;
+
+import com.example.dto.dialogflow.base.DetectIntentRequestDTO;
+import com.example.dto.dialogflow.base.DetectIntentResponseDTO;
+import reactor.core.publisher.Mono;
+
+/**
+ * Common interface for intent detection services.
+ * This abstraction allows switching between different intent detection implementations
+ * (e.g., Dialogflow, RAG) without changing dependent services.
+ */
+public interface IntentDetectionService {
+    /**
+     * Detects user intent and generates a response.
+     *
+     * @param sessionId The session identifier for this conversation
+     * @param request The request containing user input and context parameters
+     * @return A Mono of DetectIntentResponseDTO with the generated response
+     */
+    Mono<DetectIntentResponseDTO> detectIntent(
+        String sessionId,
+        DetectIntentRequestDTO request
+    );
+}