Deleting an idle scratch entry left two things behind. Headless browsers
started by a lane's e2e run kept running for days with a "(deleted)" cwd
(about 20 on one host; the process registry never knew them because they
were grandchildren of a shell that had exited). Repos whose linked
worktree lived in the entry kept a dangling registration until someone
ran `git worktree prune` by hand (10 in one repo).
The prune now lives in hermes_constants_scratch (hermes_constants keeps the
entry point). Before an idle entry is removed, same-user processes whose
cwd is inside it, or inside any scratch path that no longer exists, are
TERMed then KILLed; the deleted-cwd sweep runs on every pass so orphans
from earlier deletions are caught too. `.git` files found in the entry
name their repo, which gets `git worktree prune` after the rmtree.
cache/terminal used its own 72h fixed-age sweep; it now shares the 24h
idle rule and the subtree check. `hermes doctor` warns about cache-root
directories over 1 GiB that neither pruner covers, since finished campaign
trees parked there sat for weeks (95 GB on one host). System-prompt
scratch line updated to match.
