feat: Integrate OpenTelemetry for distributed tracing in both frontend and backend applications.

backend/pom.xml

@@ -56,6 +56,13 @@
             <artifactId>h2</artifactId>
             <scope>runtime</scope>
         </dependency>
+
+        <!-- OpenTelemetry API for custom span attributes -->
+        <dependency>
+            <groupId>io.opentelemetry</groupId>
+            <artifactId>opentelemetry-api</artifactId>
+            <version>1.49.0</version>
+        </dependency>
     </dependencies>
 
     <build>