Feat: Add HTTP Streamable Server Transport Support

[Dangoron]

Body:

Hi team,

This PR introduces support for HTTP Streamable transport to the Firecrawl MCP server. This enhancement provides an alternative way for clients to connect and interact with the server, aligning with the latest specifications and offering more flexibility for integrations.

Key Changes:

• Added a new runHTTPStreamableServer() function in src/index.ts to enable the HTTP Streamable server.
• Updated README.md to include:
  • Instructions on how to run the server in HTTP Streamable mode.
  • An example MCP client configuration for connecting via HTTP Streamable transport.
  • Relevant environment variable HTTP_STREAMABLE_SERVER and configuration examples.

This addition is in the spirit of open source and aims to enhance the capabilities and interoperability of the Firecrawl MCP server. We believe this will be a valuable addition for users looking for different transport options.

For more information on the Model Context Protocol and its specifications, please refer to the official documentation: https://modelcontextprotocol.io/specification/2025-03-26

We hope this contribution is a welcome addition to the project and look forward to your feedback!

Best regards,

Dangoron

[tradeqvest]

Hello! Will this PR eventually be merged? We are currently waiting on a reliable streamable http implementation. Thanks! @nickscamara @tomkosm

[nickscamara]

Hey @tradeqvest, yes of course, sorry about the delay! We are working on pushing improvements to our mcp earlier next month but in the meantime we should totally merge this! @tomkosm can you review it today if possible? Thanks!

[tradeqvest]

Thank you for the quick reply! Looking forward to it.

[micahstairs]

Added in https://github.com/firecrawl/firecrawl-mcp-server/commit/6817c878ce5ae72d31f0c34db44d4d92e0884d69