Two fixes for the local terminal backend on Windows (Git Bash):
1. `_drain()` in base.py: `select.select()` only works on sockets on
Windows, not pipe file descriptors. On Windows, use blocking
`os.read()` in the daemon thread instead. EOF arrives promptly
when bash exits, so this is safe.
2. `_run_bash()` in local.py: When `self.cwd` is updated from `pwd`
output, it contains Git Bash-style paths (`/c/Users/...`).
`subprocess.Popen(cwd=...)` needs a native Windows path
(`C:\Users\...`). Added a conversion before Popen.
Without these fixes, all terminal() calls on Windows return empty
output (exit code 126), and cwd tracking breaks.
Tested on Windows 11 with Git for Windows + Python 3.13.
Fixes#14638
c2d6b385f1