Fix various issues with running on Windows

[saqadri]

👋🏼 community -- there have been a bunch of issues reported with Windows. I'd love your help in enumerating some of those so I can knock them out fully. I'll reference some of the known issues, and please create/reference new issues.

If you are able to help identify/root-cause some of them, I'd be grateful for your help!

[saqadri]

#69 -- streamlit example runs into problems when run on Windows

[saqadri]

#45 -- some commands, like "npx" don't work for server invocation (current workaround: replace "npx" with "npx.cmd" in mcp_agent.config.yaml)

[saqadri]

v0.0.13 has several fixes in MCP connection manager and stdio handling which should cover this. Will reopen if folks report additional issues.