Add Pod lifecycle management, fix nav registration and context-menu bugs

Pods panel could previously only list pods - there was no way to create
one, start/stop/restart it, or attach a container to it from the UI.
Adds a "New Pod" modal (name + port mappings), a per-pod lifecycle menu
(start/stop/restart/remove), and an optional "Pod" field on the Create
Container modal to join an existing pod's network namespace. Backend
verified live against the real podman socket (/pods/create, /pods/{name}/
restart, container "pod" field).

Also fixes three real bugs found via live testing:
- Podman.page used Menu="Podman" instead of Menu="Tasks:<rank>", so the
  plugin never actually appeared in Unraid's top navigation (traced through
  PageBuilder.php/DefaultPageLayout.php/Navigation/Main.php - only pages
  registered under "Tasks" become top-level tabs).
- app.js's shared context-menu component mis-mapped every item positioned
  after a 'separator' entry to the wrong DOM element (an off-by-one against
  menu.children, which includes the separator <div>s) - so "Remove", which
  always sits after a separator, silently did nothing when clicked. Fixed
  by indexing into querySelectorAll('button') instead.
- That same menu was positioned via "position: absolute" math that assumed
  a viewport-relative containing block, but Unraid's own page wrapper
  (webGui/styles/default-base.css's ".content") sets position:relative,
  so the menu rendered far from its anchor button. Switched to
  "position: fixed" with viewport-relative coordinates.

Incidentally, pods add a hidden "infra" container that was leaking into
the plain Containers list with no working lifecycle of its own (always
"running", so its own Remove was permanently disabled) - now filtered out
via libpod's IsInfra flag. And every action-buttons table cell used
"display: flex" directly on the <td>, which browsers can size
inconsistently row to row - moved onto an inner wrapper div instead, and
bumped .podman-btn-icon's touch target size.

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

webui/plugins/podman/include/PodmanClient.php

@@ -234,6 +234,22 @@ final class PodmanClient
         return $this->request('GET', '/pods/' . rawurlencode($name) . '/json');
     }
 
+    /**
+     * POST /pods/create — takes a body of {name, portmappings, ...}.
+     * Verified live against a real podman system service: {"name":"...",
+     * "portmappings":[{"host_port":...,"container_port":...,"protocol":...}]}
+     * creates a pod with a shared infra container whose port bindings apply
+     * to every member container — see ajax/pods.php's build_pod_spec().
+     *
+     * @param array<string,mixed> $spec
+     * @return string the new pod's ID
+     */
+    public function createPod(array $spec): string
+    {
+        $result = $this->request('POST', '/pods/create', [], false, $spec);
+        return (string) ($result['Id'] ?? '');
+    }
+
     public function startPod(string $name): void
     {
         $this->request('POST', '/pods/' . rawurlencode($name) . '/start', [], true);
@@ -244,6 +260,11 @@ final class PodmanClient
         $this->request('POST', '/pods/' . rawurlencode($name) . '/stop', ['t' => (string) $timeoutSeconds], true);
     }
 
+    public function restartPod(string $name, int $timeoutSeconds = 10): void
+    {
+        $this->request('POST', '/pods/' . rawurlencode($name) . '/restart', ['t' => (string) $timeoutSeconds], true);
+    }
+
     public function removePod(string $name, bool $force = false): void
     {
         $this->request('DELETE', '/pods/' . rawurlencode($name), ['force' => $force ? 'true' : 'false'], true);