Implement MCP consumer for HTTP/WebSocket server endpoints

[Copilot]

Adds consumer implementation enabling Camel routes to act as MCP protocol servers via component URIs.

Changes

Consumer Implementation

• McpConsumer.doStart() creates Undertow HTTP/WebSocket endpoints programmatically
• Processor pipeline: size guard → HTTP validator → rate limit → JSON-RPC envelope parser → user processor → JSON serialization
• McpConsumer.doStop() handles cleanup and server shutdown
• Exchange properties populated: mcp.jsonrpc.method, mcp.jsonrpc.id, mcp.jsonrpc.type, mcp.tool.name

Configuration

• Added consumer options to McpConfiguration: websocket, sendToAll, allowedOrigins, httpMethodRestrict
• Fixed McpComponent to set URI from remaining path parameter

Testing

• McpConsumerTest covers HTTP/WebSocket startup, JSON-RPC parsing, lifecycle management
• 86/86 tests passing (4 new consumer tests)

Usage

// HTTP server
from("mcp:http://localhost:8080/mcp")
    .process(exchange -> {
        String method = exchange.getProperty("mcp.jsonrpc.method", String.class);
        // Handle MCP request, return Map response
    });

// WebSocket server
from("mcp:http://localhost:8090/mcp?websocket=true")
    .process(myMcpProcessor);

YAML:

- route:
    id: mcp-server
    from:
      uri: "mcp:http://0.0.0.0:8080/mcp"
      steps:
        - choice:
            when:
              - simple: "${exchangeProperty.mcp.jsonrpc.method} == 'tools/list'"
                steps:
                  - setBody: # MCP response

Requests require headers: Content-Type: application/json, Accept: application/json, text/event-stream

Original prompt

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This section details on the original issue you should resolve

<issue_title>Implement fully compatible MCP consumer processors (HTTP and WebSocket support, with implementation plan and acceptance test plan)</issue_title>
<issue_description>Implement the MCP consumer side so that Camel endpoints can act as MCP protocol servers, fully handling JSON-RPC 2.0 requests (e.g., initialize, tools/list, tools/call) per the MCP specification.

Requirements:

• Integrate both HTTP and WebSocket listeners (Undertow or equivalent) to receive incoming JSON-RPC requests on configurable endpoints.
• Unmarshal incoming requests as MCP protocol messages using Jackson (reusing producer-side ObjectMapper logic).
• Route requests via Camel's Processor abstraction, returning correct MCP response objects with appropriate schema and error handling.
• Ensure consumer coverage for all standard MCP methods (initialize, resources/list, resources/get, tools/call).
• Provide robust error, startup, and shutdown handling within the Camel component lifecycle.

Relevant code references for the MCP consumer processor implementation:

• McpEndpoint.java: Exposes createConsumer(Processor processor) returning a new McpConsumer.
• McpConsumer.java: Skeleton/stub for the consumer, with doStart() placeholder for HTTP/WebSocket integration.
• processor/: JSON-RPC request/response helpers and individual MCP method processors (e.g., McpResourcesGetProcessor, McpResourcesListProcessor, McpInitializeProcessor).
• README project layout: Directory and class structure overview for consumer, producer, and processor code.
• Related planning and implementation notes: CAMEL_MCP_APPS_BRIDGE_PLAN.md
• Acceptance and integration test plan: docs/TEST_PLAN.md

Acceptance Criteria:

• An MCPConsumer can be configured via endpoint URI and starts listening on both HTTP and WebSocket endpoints
• JSON-RPC 2.0 requests are correctly deserialized, routed, and responded to over both protocols
• Unit and YAML route tests cover all successful, error, and edge case behaviors for the consumer processor
• Task and architecture plan is provided in CAMEL_MCP_APPS_BRIDGE_PLAN.md (extend if necessary with consumer support sections)
• End-to-end acceptance testing is covered explicitly in docs/TEST_PLAN.md and must validate all critical MCP workflows (HTTP & WebSocket) including initialize, resources/list, resources/get, tools/list, tools/call, and error/notification flows.

See architecture notes and TODOs in McpConsumer.java, docs/architecture.md, CAMEL_MCP_APPS_BRIDGE_PLAN.md, and docs/TEST_PLAN.md for additional implementation and acceptance test background.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Implement fully compatible MCP consumer processors (HTTP and WebSocket support, with implementation plan and acceptance test plan) #4

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[rdobrik]

Use Java 21

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