`Client` connected to the unix socket once and never reconnected, so after an
opt-in self-update or `heph daemon restart` dropped the socket, every later
`call()` failed — `heph-tui` would sit on errors until relaunched (and the work
we just shipped makes restarts more frequent).
`Client` now stores the socket path and reconnects on a dropped connection,
classifying the failure to stay safe:
- write-side failure (request never reached the daemon) → reconnect + retry once;
- reply lost after sending (daemon closed mid-request) → reconnect for next time
but surface this one, so a mutation is never silently double-applied;
- genuine RPC errors are passed through untouched.
heph-tui and the CLI use `Client` unchanged, so the TUI self-heals on its next
refresh tick. Adds an integration test driving a mock daemon that drops the
connection after each request.
Closes the "heph-tui: reconnect on a dropped daemon socket" backlog task.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
