feat(mcp): migrate to Streamable HTTP transport (MCP spec 2025-03-26)

- Upgrade mcp-spring-webmvc from 0.10.0 to 0.18.1 (adds
  WebMvcStreamableServerTransportProvider alongside the legacy SSE provider)
- Add mcp-json-jackson2 0.18.1 for JacksonMcpJsonMapper adapter
- Exclude McpWebMvcServerAutoConfiguration (SSE transport) via
  spring.autoconfigure.exclude; register WebMvcStreamableServerTransportProvider
  and its RouterFunction manually in McpConfig so Spring AI's
  McpServerAutoConfiguration picks up the correct transport bean
- Remove sse-message-endpoint / sse-endpoint from application.yml;
  all MCP traffic now flows through POST+GET /mcp
- Remove McpSseMethodNotAllowed workaround from WebConfig and drop
  'sse' from SPA fallback exclusions (no longer needed)

Clients should connect with type: http at https://trueref.sal.giize.com/mcp

trueref-adapters/pom.xml

@@ -44,12 +44,27 @@
             <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
         </dependency>
 
-        <!-- Spring AI MCP server (Streamable HTTP) -->
+        <!-- Spring AI MCP server — tool/resource registration and McpSyncServer wiring.
+             McpWebMvcServerAutoConfiguration (SSE transport) is excluded in application.yml;
+             the Streamable HTTP transport is wired manually in McpConfig. -->
         <dependency>
             <groupId>org.springframework.ai</groupId>
             <artifactId>spring-ai-starter-mcp-server-webmvc</artifactId>
         </dependency>
 
+        <!-- MCP Java SDK 0.18.1: provides WebMvcStreamableServerTransportProvider.
+             Overrides the 0.10.0 version pulled in by spring-ai-starter-mcp-server-webmvc. -->
+        <dependency>
+            <groupId>io.modelcontextprotocol.sdk</groupId>
+            <artifactId>mcp-spring-webmvc</artifactId>
+            <version>0.18.1</version>
+        </dependency>
+        <dependency>
+            <groupId>io.modelcontextprotocol.sdk</groupId>
+            <artifactId>mcp-json-jackson2</artifactId>
+            <version>0.18.1</version>
+        </dependency>
+
         <!-- H2 + Flyway -->
         <dependency>
             <groupId>com.h2database</groupId>