Follow-up on top of @rahlquist's terminal.temp_dir knob (#97182): the
default itself now avoids RAM-backed tmpfs. Resolution order on the
local backend: terminal.temp_dir > TMPDIR/TMP/TEMP > HERMES_HOME/cache/
terminal (managed, pruned) > /tmp fallback. Pruning: hourly via gateway
housekeeping + once-per-process best-effort sweep; hermes_bg_* triplets
are aged as a group so a live server's fresh .log protects its .pid.
Some Linux distros (notably RAM-based tmpfs /tmp on several Arch-based
setups) cap the temp directory at a small size, so Hermes runs out of
space for session temp files (background logs/pid/exit files, code-
execution sandboxes). Add a terminal.temp_dir config key that points
these at real storage.
- Add terminal.temp_dir default (empty) in config_defaults.py
- Bridge it to TERMINAL_TEMP_DIR via TERMINAL_CONFIG_ENV_MAP
- Honor TERMINAL_TEMP_DIR first in LocalEnvironment.get_temp_dir(),
falling through to TMPDIR//tmp//gettempdir when unset/invalid
- Add tests covering override, process-env, missing-dir, and empty