refactor(transport): Replace SseEmitter with queue-based SSE implementation in WebMvc transport

Replaces Spring's SseEmitter with a custom BlockingQueue-based SSE implementation in
WebMvcSseServerTransport for improved event delivery control and connection management.

The new implementation:
- Uses BlockingQueue for reliable event queuing and delivery
- Adds proper session management with dedicated SSEEvent record
- Improves error handling and timeout management
- Adds comprehensive integration tests

Resolves #57

samples/spring-ai-mcp-webmvc-sample/pom.xml

@@ -27,6 +27,13 @@
             <artifactId>mcp-webmvc-sse-transport</artifactId>
             <version>${spring-ai-mcp.version}</version>
         </dependency>
+        
+        <!-- Used only for the client webflux transport -->
+        <dependency>
+            <groupId>org.springframework.experimental</groupId>
+            <artifactId>mcp-webflux-sse-transport</artifactId>
+            <version>${spring-ai-mcp.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.springframework.experimental</groupId>
             <artifactId>spring-ai-mcp</artifactId>