fix(packaging): address review findings for #44

- nfpm.yaml: type:config → config_noreplace (RPM noreplace semantics)
- nfpm.yaml: type:ghost → type:dir for /var/lib/fenris (deb compatibility)
- postinst.sh/rpm/post.sh: fix timer restart — capture running unit before
  daemon-reload so the diff actually detects changes
- README: fix Python floor to ≥3.10 (was ≥3.9, inconsistent with Makefile)
- signing-key-ceremony.md: fix stale claim about nfpm signing RPMs
  (actual path is post-build rpmsign)
- tests/conftest.py: extract shared _get_version() and _read() helpers
- tests: wire up to shared conftest helpers
- release.yml: extract VERSION once via GITHUB_OUTPUT step

Co-authored-by: CommandCodeBot <noreply@commandcode.ai>

README.md

@@ -8,7 +8,7 @@ Fenris is a persistent TUI monitor backed by a short-lived privileged collector
 
 ## Requirements
 
-- **Python ≥ 3.9** (verified at install time; ≥ 3.10 for packages)
+- **Python ≥ 3.10** (verified at install time)
 - **smartmontools** (`smartctl` — verified at install time)
 - **systemd** with a polkit agent (the collector runs as root oneshot; elevation is exclusively polkit)