feat: Add MCP server with Server stdio/sse transport improve MCP client

- Implement MCP server with async/sync support and builder pattern configuration
 - Add Server stdio/SSE transport layers with robust error handling
 - Convert McpClient and McpServer to interfaces for better extensibility
 - Add sampling capabilities for LLM interactions (text/image)
 - Implement dynamic root management and runtime tool management
 - Add comprehensive prompt and resource capabilities
 - Add support for dynamic root management (add/remove roots at runtime)

 Architecture Changes

 - Introduce registration records for tools, resources, and prompts
 - Improve thread safety with concurrent collections
 - Enhance resource template handling
 - Implement builder patterns for Server/Client capabilities
 - Add support for server capabilities and implementation info

Transport Layer:
 - Implement SseServerTransport with SSE endpoints
 - Add StdioServerTransport for process-based communication
 - Reorganize transport packages for better organization
 - Improve transport error handling and shutdown processes

Documentation:

 - Add detailed MCP reference documentation
 - Include architecture diagrams and API documentation
 - Add comprehensive test coverage for all components
 - Include sample projects demonstrating stdio/SSE transports

BREAKING CHANGES:

 Transport Package Reorganization

 - Move StdioClientTransport to o.s.ai.mcp.client.transport
 - Move SseClientTransport to o.s.ai.mcp.client.transport
 - Move ServerParameters to o.s.ai.mcp.client.transport
 - StdioClientTransport.errorHandler changed to private with
   setter method Migration: Use setErrorHandler() method
   instead of direct field access

 API Changes

 - Replace static factory methods with builder pattern
 - Update ServerCapabilities to use builder pattern
 - Make StdioClientTransport.errorHandler private with setter
 - Replace rootsListProvider with direct root management
 - Remove deprecated static factory methods

Resolves #27,#25,#24,#11
Related to #12

docs/ref-index.md

@@ -0,0 +1,91 @@
+# Spring AI MCP Reference Documentation
+
+This documentation covers the Spring AI implementation of the Model Context Protocol (MCP) specification. The implementation follows the [official MCP specification](https://spec.modelcontextprotocol.io/specification/).
+
+## Component Hierarchy
+
+### 1. Transport Layer
+[Transport](ref-transport.md)
+- McpTransport Interface
+- Transport Implementations (SSE, STDIO)
+- Message Serialization/Deserialization
+
+### 2. Session Layer
+[Session Management](ref-session.md)
+- McpSession Interface
+- DefaultMcpSession Implementation
+- Uses McpTransport for communication
+
+### 3. High-Level Components
+Both components operate at the same level, using McpSession internally:
+
+[Client](ref-client.md)
+- McpClient Factory
+- Synchronous and Asynchronous Implementations
+- Client Configuration and Builder Pattern
+
+[Server](ref-server.md)
+- McpServer Factory
+- Synchronous and Asynchronous Implementations
+- Server Configuration and Builder Pattern
+
+### 4. Supporting Components
+
+[Error Handling](ref-errors.md)
+- McpError
+- Error Codes and Handling
+- Exception Hierarchy
+
+
+## Component Relationships
+
+```
+┌─────────────┐    ┌─────────────┐
+│  McpClient  │    │  McpServer  │
+└─────────────┘    └─────────────┘
+       │                  │
+       └─────────┬────────┘
+                 │
+         ┌───────────────┐
+         │   McpSession  │
+         └───────────────┘
+                 │
+         ┌───────────────┐
+         │  McpTransport │
+         └───────────────┘
+```
+
+## Package Organization
+
+The implementation is organized under the `org.springframework.ai.mcp` package with the following structure:
+
+- `org.springframework.ai.mcp.spec` - Core interfaces and classes
+  - McpTransport
+  - McpSession
+  - McpSchema
+  - McpError
+- `org.springframework.ai.mcp.client` - Client implementations
+  - McpClient
+  - McpAsyncClient
+  - McpSyncClient
+  - Client-specific transports
+- `org.springframework.ai.mcp.server` - Server implementations
+  - McpServer
+  - McpAsyncServer
+  - McpSyncServer
+  - Server-specific transports
+- `org.springframework.ai.mcp.util` - Utility classes
+  - Assert
+  - Utils
+
+## Key Features
+
+- Synchronous and Asynchronous implementations
+- Multiple transport options (SSE, STDIO)
+- Comprehensive error handling
+- Builder pattern for configuration
+- Reactive programming support with Project Reactor
+- Type-safe message handling
+- Resource and prompt management
+- Tool discovery and execution
+- Change notification system