Shell escape: pipe stdin for interactive native commands

[stalep]

Summary

When shell escape (!command) is used to run an interactive native command that reads from stdin (e.g., a .bat file with pause or set /p, or Unix commands like less, vim, python), the command hangs because the current implementation does not connect the terminal's input to the process's stdin.

Current behavior

The executeNativeCommand() method in ReadlineConsole reads the process's stdout and pipes it through Connection.write(), but does NOT connect the connection's input to the process's stdin. Interactive commands that need user input block indefinitely.

Expected behavior

Interactive native commands should receive terminal input:

[myshell]$ !python
Python 3.12.0
>>> print("hello")
hello
>>> exit()
[myshell]$

Proposed approach

1. Temporarily redirect the connection's stdin handler to write to the process's stdin stream
2. Continue reading the process's stdout and writing to the connection
3. Handle Ctrl-C by destroying the native process and returning to the aesh prompt
4. Restore the original stdin handler when the process completes

Alternative: inheritIO() — for local terminals, ProcessBuilder.inheritIO() supports fully interactive programs but does NOT work for remote connections (SSH, WebSocket). Could auto-detect local vs remote.

Context

Follow-up to #566 (shell escape via ! prefix).