agentcore dev add flag to adjust timeout

Hi,

I am experiencing the issue that I receive a timeout after 180 seconds when running agentcore dev to invoke my agent locally. The timeout for the HTTP request is hardcoded to 180 seconds and I would appreciate if there would be a flag that can be passed to agentcore dev to adjust this timeout.

e.g.

`agentcore dev --timeout 600 // for 600 seconds`

Start at the agentcore dev CLI entry point and trace the local invocation path to find where the 180-second HTTP timeout is set. Add support for the requested timeout flag, then verify that running agentcore dev with a larger value allows requests to wait longer without changing the default behavior.

Written by the indexing model from the issue text.