Fix python breakpoints in PaSh server

Currently, using the `breakpoint` built-in function in the PaSh server code triggers an EOF error when it attempts to read from stdin. I don’t know why this occurs — I don’t think the server ever reads from stdin. It’d be convenient if breakpoints worked for debugging.

Start by reproducing a Python breakpoint in the PaSh server and observe the EOF error when it reads from stdin. Trace the server's stdin handling to identify why breakpoint debugging cannot receive input; done means breakpoints work without the EOF failure.

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