fix(mcp): align SDK and wire streamable server manually

- align all io.modelcontextprotocol.sdk artifacts to 0.18.1 via
  dependencyManagement so Spring AI transitives no longer pull mcp 0.10.0
- exclude Spring AI's legacy MCP server/webmvc auto-config, which is binary-
  incompatible with the 0.18.1 streamable transport APIs
- build McpSyncServer directly against WebMvcStreamableServerTransportProvider
  and adapt Spring AI ToolCallbacks to MCP SyncToolSpecifications manually
- keep /mcp as the sole Streamable HTTP endpoint for both initialize/tool calls
  and optional SSE event streams
- update MCP transport documentation to match the new runtime

Validated locally with:
- POST /mcp initialize -> HTTP 200 + Mcp-Session-Id
- POST /mcp tools/list -> returns resolve-library-id + get-library-docs

pom.xml

@@ -33,6 +33,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
         <spring-ai.version>1.0.0</spring-ai.version>
+        <mcp.sdk.version>0.18.1</mcp.sdk.version>
         <springdoc.version>2.8.6</springdoc.version>
         <jgit.version>7.3.0.202506031305-r</jgit.version>
         <lucene.version>10.4.0</lucene.version>
@@ -83,6 +84,29 @@
                 <scope>import</scope>
             </dependency>
 
+            <!-- MCP Java SDK: keep Spring AI's transitives and our direct transport/json
+                 dependencies on one compatible version line. -->
+            <dependency>
+                <groupId>io.modelcontextprotocol.sdk</groupId>
+                <artifactId>mcp</artifactId>
+                <version>${mcp.sdk.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.modelcontextprotocol.sdk</groupId>
+                <artifactId>mcp-core</artifactId>
+                <version>${mcp.sdk.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.modelcontextprotocol.sdk</groupId>
+                <artifactId>mcp-spring-webmvc</artifactId>
+                <version>${mcp.sdk.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.modelcontextprotocol.sdk</groupId>
+                <artifactId>mcp-json-jackson2</artifactId>
+                <version>${mcp.sdk.version}</version>
+            </dependency>
+
             <!-- 3rd-party -->
             <dependency>
                 <groupId>org.springdoc</groupId>