Add reproducible build system, native Unraid plugin, and WebUI

- versions.env pins podman, conmon, crun, netavark, aardvark-dns, passt,
  and fuse-overlayfs to verified upstream source checksums; SlackBuild
  recipes, scripts/build-packages.sh, checksums.sh, release.sh, and
  update-versions.sh implement the reproducible pipeline; GitHub Actions
  workflows build in a Slackware container and publish releases without
  committing any binaries.

- plugin/podman.plg installs/updates/removes all eight packages (the
  seven components plus the plugin's own unraid-podman scaffolding
  package) via upgradepkg, using the official Unraid array-event hook
  mechanism (event/disks_mounted, event/stopping) instead of editing
  /boot/config/go. rc.podman and the sbin/ helper scripts implement
  storage creation, config seeding/sync, preflight checks, autostart
  with per-container Safe-Mode, and package verify/update/rollback.

- webui/plugins/podman implements the Dashboard, Containers, Pods,
  Images, Volumes, Networks, Logs, Terminal, Compose, and Settings
  panels against the approved mockup (webui/mockups/prototype.html),
  talking to podman system service exclusively via PodmanClient.php
  (libpod REST API over the Unix socket), with two documented
  exceptions: Terminal's one-shot exec model and Compose's use of the
  podman compose CLI, since libpod has no REST equivalent for either.

- docs/ARCHITECTURE.md and docs/ROADMAP.md record the design decisions
  and honest current status (syntax-checked, unit- and
  integration-tested against fake sockets/servers; not yet run against
  a real Unraid/Podman/Slackware system).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,46 @@
+# --- Slackware package build artifacts ---
+packages/**/src/
+packages/**/pkg/
+packages/**/work/
+packages/**/*.txz
+packages/**/*.tgz
+packages/**/*.txz.md5
+packages/**/*.tgz.md5
+
+# --- Build / release output ---
+/dist/
+/build/
+/release/
+*.plg.bak
+
+# --- Logs ---
+*.log
+/scripts/dev/*.log
+
+# --- Editor / IDE ---
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# --- OS cruft ---
+.DS_Store
+Thumbs.db
+
+# --- WebUI tooling (once JS/PHP tooling is added) ---
+node_modules/
+vendor/
+composer.lock
+package-lock.json
+
+# --- Local/dev config overrides, never commit real secrets ---
+*.local
+.env
+.env.*
+config/*.secret
+
+# --- Downloaded upstream sources used during package builds ---
+packages/**/*.tar.gz
+packages/**/*.tar.xz
+packages/**/*.tar.bz2