* fix(desktop/windows): stop racing our own backend during in-app update
The Windows in-app update (Update button -> hermes-setup.exe --update handoff)
bricked because it raced a still-locked hermes.exe: the desktop quit
fire-and-forget without reaping its backend child + grandchildren, so when
the updater ran `hermes update`, the venv shim was still open. The quarantine
rename then failed, uv's `pip install -e .` hit "Access is denied", the git
path bailed to a full ZIP re-download, and the deps still couldn't write the
locked shim -- leaving a half-applied install. macOS is fine because it never
blocks REPLACE on a running executable.
Three coordinated fixes restore Mac-style parity (click Update -> progress ->
relaunch, no terminal):
A. Desktop (main.cjs): before spawning the updater, releaseBackendLockForUpdate()
tree-kills the primary + pool backends (taskkill /T /F on Windows, to catch
REPL/pty/gateway grandchildren that SIGTERM misses) and polls the venv shim
until it is actually writable (bounded 15s) -- so the lock is gone before we
hand off. Also fixes resolveHermesCliBinary to use venv\Scripts\hermes.exe on
Windows.
B. Updater (update.rs): wait_for_venv_free no longer "proceeds anyway" on
timeout -- it force-kills any lingering hermes.exe (excluding itself) and
re-checks, so a straggler can't doom the install.
C. Updater (update.rs): pass --force to `hermes update`. By contract the desktop
has exited + waited, and the wait force-kills stragglers, so the running-exe
guard would only produce a false "Hermes is still running" dead-end.
Verified: node --check on main.cjs, cargo check on the updater (clean), and the
Windows-gated taskkill body type-checks standalone. Field repro: ryanc's
update.log (manual + handoff both hit the same lock cascade).
* review: scope backend kill+wait to Windows; drop meaningless POSIX pgid kill
98528c78c1