feat: add HTTP/REST transport for MCP servers

- Refactor server to use a generic transport interface
- Add HttpTransport for JSON-RPC and REST over HTTP
- Move existing STDIO logic into a StdioTransport
- Enable dual-mode (STDIO/HTTP) via command-line flags
- Add new examples and docs for HTTP server usage

examples/mcp/simple_http/server.vsh

@@ -0,0 +1,178 @@
+#!/usr/bin/env -S v -n -w -cg -d use_openssl -d json_no_inline_sumtypes -enable-globals run
+
+import freeflowuniverse.herolib.mcp
+import freeflowuniverse.herolib.mcp.transport
+import freeflowuniverse.herolib.schemas.jsonrpc
+import freeflowuniverse.herolib.schemas.jsonschema
+import x.json2
+import os
+
+// Simple tool handler using json2.Any (required by MCP framework)
+fn simple_echo_handler(arguments map[string]json2.Any) !mcp.ToolCallResult {
+	// Extract message from arguments
+	message := if 'message' in arguments {
+		arguments['message'].str()
+	} else {
+		'No message provided'
+	}
+
+	return mcp.ToolCallResult{
+		is_error: false
+		content:  [
+			mcp.ToolContent{
+				typ:  'text'
+				text: 'Echo: ${message}'
+			},
+		]
+	}
+}
+
+// Simple math handler using json2.Any
+fn simple_add_handler(arguments map[string]json2.Any) !mcp.ToolCallResult {
+	// Extract numbers
+	num1 := if 'num1' in arguments {
+		arguments['num1'].f64()
+	} else {
+		return mcp.ToolCallResult{
+			is_error: true
+			content:  [mcp.ToolContent{
+				typ:  'text'
+				text: 'Missing num1'
+			}]
+		}
+	}
+
+	num2 := if 'num2' in arguments {
+		arguments['num2'].f64()
+	} else {
+		return mcp.ToolCallResult{
+			is_error: true
+			content:  [mcp.ToolContent{
+				typ:  'text'
+				text: 'Missing num2'
+			}]
+		}
+	}
+
+	result := num1 + num2
+	return mcp.ToolCallResult{
+		is_error: false
+		content:  [
+			mcp.ToolContent{
+				typ:  'text'
+				text: 'Result: ${result}'
+			},
+		]
+	}
+}
+
+// Parse command line arguments
+fn parse_args() (transport.TransportMode, int) {
+	args := os.args[1..]
+	mut mode := transport.TransportMode.stdio
+	mut port := 8080
+
+	for i, arg in args {
+		match arg {
+			'--http' {
+				mode = .http
+			}
+			'--port' {
+				if i + 1 < args.len {
+					port = args[i + 1].int()
+				}
+			}
+			else {}
+		}
+	}
+
+	return mode, port
+}
+
+fn main() {
+	// Parse command line arguments
+	mode, port := parse_args()
+
+	// Create a simple backend with basic tools
+	backend := mcp.MemoryBackend{
+		tools:         {
+			'echo': mcp.Tool{
+				name:         'echo'
+				description:  'Echo back a message'
+				input_schema: jsonschema.Schema{
+					typ:        'object'
+					properties: {
+						'message': jsonschema.SchemaRef(jsonschema.Schema{
+							typ:         'string'
+							description: 'Message to echo back'
+						})
+					}
+					required:   ['message']
+				}
+			}
+			'add':  mcp.Tool{
+				name:         'add'
+				description:  'Add two numbers'
+				input_schema: jsonschema.Schema{
+					typ:        'object'
+					properties: {
+						'num1': jsonschema.SchemaRef(jsonschema.Schema{
+							typ:         'number'
+							description: 'First number'
+						})
+						'num2': jsonschema.SchemaRef(jsonschema.Schema{
+							typ:         'number'
+							description: 'Second number'
+						})
+					}
+					required:   ['num1', 'num2']
+				}
+			}
+		}
+		tool_handlers: {
+			'echo': simple_echo_handler
+			'add':  simple_add_handler
+		}
+	}
+
+	// Create transport configuration
+	transport_config := transport.TransportConfig{
+		mode: mode
+		http: transport.HttpConfig{
+			port:     port
+			protocol: .both // Support both JSON-RPC and REST
+		}
+	}
+
+	// Create and start the server
+	mut server := mcp.new_server(backend, mcp.ServerParams{
+		config:    mcp.ServerConfiguration{
+			server_info: mcp.ServerInfo{
+				name:    'simple_http_example'
+				version: '1.0.0'
+			}
+		}
+		transport: transport_config
+	})!
+
+	if mode == .http {
+		println('🚀 Starting HTTP MCP server on port ${port}')
+		println('')
+		println('📡 Endpoints:')
+		println('  JSON-RPC: http://localhost:${port}/jsonrpc')
+		println('  Health:   http://localhost:${port}/health')
+		println('  Tools:    http://localhost:${port}/api/tools')
+		println('')
+		println('🧪 Test commands:')
+		println('  curl http://localhost:${port}/health')
+		println('  curl http://localhost:${port}/api/tools')
+		println('  curl -X POST http://localhost:${port}/api/tools/echo/call -H "Content-Type: application/json" -d \'{"message":"Hello World"}\'')
+		println('  curl -X POST http://localhost:${port}/api/tools/add/call -H "Content-Type: application/json" -d \'{"num1":5,"num2":3}\'')
+		println('')
+	} else {
+		println('📟 Starting STDIO MCP server')
+		println('Ready for JSON-RPC messages on stdin...')
+	}
+
+	server.start()!
+}