Add signed-package verification and anti-rootkit cross-view (v0.7)

Closes the tamper-evidence loop with two trust anchors the attacker can't
forge from userland:

- pkgdb Layer 2: verify on-disk files against the .MTREE in the *signed*
  cache package, surviving a rewritten local checksum DB. Rotating-sample
  cadence keeps it affordable; flags pkg_signature_mismatch (sid 100027)
  and SigLevel downgrades (sid 100026). Fixes parse_mtree, which required
  type=file on every line and so matched nothing on real pacman MTREEs
  (which use a /set type=file default with bare file entries).
- rootcheck: anti-rootkit cross-view — hidden processes, modules, ports,
  and promiscuous interfaces, each caught by diffing two views of the
  same state (sids 100022-100025).

Wired both through config, the daemon (off-loop slow cadence), and CLI
(pkgdb-verify, rootcheck). 14 new tests (95 total). Docs + version bump.

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

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "enodia-sentinel"
-version = "0.6.0"
+version = "0.7.0"
 description = "Host intrusion-detection daemon — signature-based detection of reverse shells, LD_PRELOAD rootkits, fileless malware, and persistence tampering"
 readme = "README.md"
 requires-python = ">=3.11"