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>

webui/plugins/podman/ajax/networks.php

@@ -0,0 +1,93 @@
+<?php
+/**
+ * ajax/networks.php
+ *
+ * Backs the Networks panel. See docs/ARCHITECTURE.md section 8 for why
+ * networks created here are netavark-backed and deliberately isolated
+ * from Docker's own docker0/custom-network space.
+ *
+ * Actions (?action=...):
+ *   list     GET  -> normalized network list with subnet/gateway/usage
+ *   create   POST {"name": "...", "driver": "bridge", "subnet": "...", "gateway": "..."}
+ *   remove   POST {"name": "...", "force": false}
+ */
+
+declare(strict_types=1);
+
+require __DIR__ . '/../include/bootstrap.php';
+
+$action = $_GET['action'] ?? '';
+
+switch ($action) {
+    case 'list':
+        podman_json_response(networks_list($client));
+        break;
+
+    case 'create':
+        $body = podman_read_json_body();
+        $name = (string) ($body['name'] ?? '');
+        if ($name === '') {
+            podman_json_error('Missing name in request body', 400);
+        }
+        podman_json_response($client->createNetwork(
+            $name,
+            (string) ($body['driver'] ?? 'bridge'),
+            isset($body['subnet']) ? (string) $body['subnet'] : null,
+            isset($body['gateway']) ? (string) $body['gateway'] : null
+        ));
+        break;
+
+    case 'remove':
+        $body = podman_read_json_body();
+        $name = (string) ($body['name'] ?? '');
+        if ($name === '') {
+            podman_json_error('Missing name in request body', 400);
+        }
+        // podman0, the default bridge, refuses removal API-side — no
+        // special-casing needed here, PodmanApiException surfaces podman's
+        // own rejection message as-is.
+        $client->removeNetwork($name, (bool) ($body['force'] ?? false));
+        podman_json_response(['status' => 'removed']);
+        break;
+
+    default:
+        podman_json_error("Unknown action '{$action}'", 400);
+}
+
+/** @return array<int,array<string,mixed>> */
+function networks_list(PodmanClient $client): array
+{
+    $raw = $client->listNetworks();
+
+    $usageCounts = [];
+    foreach ($client->listContainers(true) as $c) {
+        $nets = $c['Networks'] ?? [];
+        if (is_array($nets)) {
+            foreach ($nets as $netName) {
+                if (is_string($netName)) {
+                    $usageCounts[$netName] = ($usageCounts[$netName] ?? 0) + 1;
+                }
+            }
+        }
+    }
+
+    $out = [];
+    foreach ($raw as $n) {
+        $name = (string) ($n['name'] ?? '');
+        $subnets = $n['subnets'] ?? [];
+        $subnet = is_array($subnets) && count($subnets) > 0 ? (string) ($subnets[0]['subnet'] ?? '') : '';
+        $gateway = is_array($subnets) && count($subnets) > 0 ? (string) ($subnets[0]['gateway'] ?? '') : '';
+
+        $out[] = [
+            'name' => $name,
+            'driver' => (string) ($n['driver'] ?? 'bridge'),
+            'subnet' => $subnet,
+            'gateway' => $gateway,
+            'isDefault' => $name === 'podman',
+            'containers' => $usageCounts[$name] ?? 0,
+        ];
+    }
+
+    usort($out, static fn($a, $b) => strcmp($a['name'], $b['name']));
+    return $out;
+}