On Windows with Chinese locale (GBK), subprocess.run(text=True) without
explicit encoding causes UnicodeDecodeError crashes. This fix adds
encoding='utf-8', errors='replace' to all subprocess.run() and
subprocess.Popen() calls that use text=True across 76 non-test Python files.
Fixes#53428 (master tracker for Windows GBK locale crash).
Note: credential_pool.py and electron changes excluded per reviewer request —
those will be submitted as separate focused PRs.