docs: clarify transport support in README overview

[hrntknr]

Summary

Update README to clarify that the proxy supports all MCP transports (stdio, SSE, HTTP) with appropriate handling for each. This improves clarity about the proxy's transport capabilities.

Type of Change

• docs: Documentation only changes

Related Issues

[Copilot]

Pull Request Overview

Updates the README documentation to clarify the proxy's transport support capabilities. The changes improve clarity about how the proxy handles different MCP transport protocols (stdio, SSE, HTTP) and what transformations occur for each.

• Clarified that all three MCP transport types (stdio, SSE, HTTP) are supported
• Explained how stdio traffic is converted to /mcp endpoint while SSE/HTTP are proxied as-is
• Updated terminology from "streamable HTTP" to simply "HTTP" for consistency

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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