Re-architect Sentinel as a zero-dependency Python package

Port the bash prototype to a structured, testable Python codebase while
preserving the same control loop and the seven detection signatures. The bash
implementation stays in src/ as the regression oracle.

Highlights:
- enodia_sentinel/ package (stdlib only — no runtime deps):
  - detectors/ : one pure function per signature, detect(state, cfg)->Alerts
  - system.py  : SystemState — one cached /proc + ss snapshot per sweep,
                 fully injectable so detectors are unit-testable
  - daemon.py  : sweep loop, in-process cooldown dedup, threaded snapshot
                 capture, and a SUID filesystem scan moved OFF the loop
                 thread onto a slow background cadence
  - snapshot.py: forensic text + JSON sidecar with per-signature IR guidance
  - config.py  : dataclass config via TOML + env overrides
  - netutil.py : public-IP / CIDR logic via stdlib ipaddress
- tests/ : 25 stdlib-unittest cases (no root, no /proc, no ss needed)
- TOML config, launcher wrapper, Makefile (pip-free install), hardened
  systemd unit (env-resolved ExecStart), updated PKGBUILD, rewritten README

Performance: per-sweep cost ~200 ms (shared cached state); the multi-second
SUID walk no longer blocks detection. scandir-based walk replaces os.walk.

Verified on Arch: all 7 detectors fire on red-team drills (reverse_shell,
ld_preload, deleted_exe, new_listener, new_suid confirmed live end-to-end),
no false positives on a clean sweep, 25/25 tests pass.

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

packaging/PKGBUILD

@@ -1,24 +1,27 @@
 # Maintainer: Enodia
 pkgname=enodia-sentinel
-pkgver=0.1.0
+pkgver=0.2.0
 pkgrel=1
 pkgdesc="Host intrusion-detection daemon — signature-based detection of reverse shells, LD_PRELOAD rootkits, fileless malware, and persistence tampering"
 arch=('any')
 url="https://github.com/Enodia/enodia-sentinel"
 license=('MIT')
-depends=('bash' 'iproute2' 'procps-ng')
+depends=('python>=3.11' 'iproute2' 'procps-ng')
 optdepends=('bpftrace: execve tracing of short-lived processes in snapshots'
             'libnotify: desktop notifications on alert')
-backup=('etc/enodia-sentinel.conf')
+backup=('etc/enodia-sentinel.toml')
 source=()
 sha256sums=()
 
 package() {
     cd "$startdir/.."
-    install -Dm755 src/sentinel.sh      "$pkgdir/usr/bin/sentinel.sh"
+    # Install the stdlib-only package as a directory + launcher under /usr.
+    install -d "$pkgdir/usr/lib/enodia-sentinel"
+    cp -r enodia_sentinel "$pkgdir/usr/lib/enodia-sentinel/"
+    install -Dm755 packaging/enodia-sentinel.wrapper "$pkgdir/usr/bin/enodia-sentinel"
     install -Dm755 src/sentinel-redteam "$pkgdir/usr/bin/sentinel-redteam"
     install -Dm644 systemd/enodia-sentinel.service "$pkgdir/usr/lib/systemd/system/enodia-sentinel.service"
-    install -Dm644 config/enodia-sentinel.conf "$pkgdir/etc/enodia-sentinel.conf"
+    install -Dm644 config/enodia-sentinel.toml "$pkgdir/etc/enodia-sentinel.toml"
     install -Dm644 LICENSE "$pkgdir/usr/share/licenses/$pkgname/LICENSE"
     install -dm750 "$pkgdir/var/log/enodia-sentinel"
 }