Enodia Sentinel v0.1 — bash host-IDS prototype

Poll-based host intrusion-detection daemon modeled on freeze-watcher's
sample→trigger→snapshot→classify loop, with security signatures instead
of performance ones:

- reverse_shell  (interpreter with a network socket on stdio)
- ld_preload     (/etc/ld.so.preload or LD_PRELOAD in writable dirs)
- deleted_exe    (process running from a deleted/memfd binary)
- new_listener   (listening port absent from startup baseline)
- new_suid       (new SUID/SGID binary; critical in writable dirs)
- persistence    (cron/systemd/authorized_keys/rc-file changes)
- suspicious_egress (interpreter holding an outbound public connection)

Each capture writes a forensic snapshot with per-signature incident-
response guidance. Includes a safe, self-cleaning red-team harness
(sentinel-redteam), hardened systemd unit, config, Makefile, and Arch
packaging.

Tested on Arch: detectors fire on drills, no false positives on a clean
sweep, sweep cost optimized from ~15s to ~1s via batched syscalls and a
gated filesystem-wide SUID scan.

This bash implementation is retained as the regression oracle for the
forthcoming Python rewrite.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

LICENSE

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+MIT License
+
+Copyright (c) 2026 Enodia
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
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+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
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+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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+SOFTWARE.