The CLI key bootstrap wrote to ~/.omniroute/.env ignoring DATA_DIR, so users with a
custom DATA_DIR (incl. Docker-style setups) lost the key across restarts. It also
regenerated a fresh key whenever STORAGE_ENCRYPTION_KEY was unset — even when an encrypted
storage.sqlite already existed — locking users out. Now writes to DATA_DIR and refuses to
auto-generate when a database is already present (mirrors server bootstrapEnv guard).
Reported by Daniel Nach; original key persistence by @Chewji9875.
