Log headers in curl initialize requests

The user needs the `mcp-session-id` header, so we should log headers.

Author: sambostock

examples/http_server.rb

@@ -156,7 +156,7 @@ def template(args, server_context:)
 puts "Starting MCP HTTP server on http://localhost:9292"
 puts "Use POST requests to initialize and send JSON-RPC commands"
 puts "Example initialization:"
-puts '  curl -X POST http://localhost:9292 -H "Content-Type: application/json" -d \'{"jsonrpc":"2.0","method":"initialize","id":1,"params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}\''
+puts '  curl -i -X POST http://localhost:9292 -H "Content-Type: application/json" -d \'{"jsonrpc":"2.0","method":"initialize","id":1,"params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}\''
 puts ""
 puts "The server will return a session ID in the Mcp-Session-Id header."
 puts "Use this session ID for subsequent requests."

examples/streamable_http_server.rb

@@ -147,7 +147,7 @@ def call(message:, delay: 0)
 puts "Testing SSE:"
 puts ""
 puts "1. Initialize session:"
-puts '   curl -X POST http://localhost:9393 -H "Content-Type: application/json" \\'
+puts '   curl -i -X POST http://localhost:9393 -H "Content-Type: application/json" \\'
 puts '     -d \'{"jsonrpc":"2.0","method":"initialize","id":1,"params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"sse-test","version":"1.0"}}}\''
 puts ""
 puts "2. Connect SSE stream (use the session ID from step 1):"