Wire up GitHub Actions for deb/brew build, test, and release

- Fix debian.yml: pin nfpm version, add permissions, improve test job
  with user creation, init test, and status check
- Fix homebrew.yml: use PyPI JSON API (macOS-compatible, no grep -oP),
  wait for PyPI availability on release, use generated formula not template,
  add Linux (Linuxbrew) test job alongside macOS
- Add release.yml orchestrator: pip → deb + brew + docker in order
- Add workflow_call triggers to pip.yml and docker.yml
- Fix build_brew.sh: replace grep -oP with Python-based PyPI API,
  add on_linux deps (pkg-config, openssl, libffi)
- Fix setup.sh: use GitHub API to find correct .deb download URL
  (filename includes version number)
- Fix postinstall.sh: create archivebox system user, pin version from
  package, check for systemd before daemon-reload
- Fix preremove.sh: stop service before removal, check for systemd
- Fix install.sh: fallback to latest if pinned version not on PyPI
- Add on_linux deps to brew formula for Linuxbrew support
- Tested: .deb builds, installs, creates user, runs archivebox init

https://claude.ai/code/session_01Vx1EsNrNySgsc8Y67dGzCn

brew_dist/archivebox.rb

@@ -23,6 +23,12 @@ class Archivebox < Formula
   depends_on "ripgrep"
   depends_on "yt-dlp"
 
+  on_linux do
+    depends_on "pkg-config" => :build
+    depends_on "openssl@3"
+    depends_on "libffi"
+  end
+
   # Python dependency resource blocks are auto-generated by bin/build_brew.sh
   # using homebrew-pypi-poet. Run that script to populate this section.
   # AUTOGENERATED_RESOURCES_START