Add filesystem scan trigger and version badge features

Implements optional filesystem scan triggering for Plex and Audiobookshelf after file organization, with new settings in the admin UI, setup wizard, and API. Updates documentation to reflect scan trigger options and improved file organization/cleanup logic. Refactors dropdown menus to use smart positioning and portals for better UX. Adds a version API route and a VersionBadge component to display build info in the header. Updates Docker build to inject version metadata.

src/components/ui/VersionBadge.tsx

@@ -0,0 +1,51 @@
+/**
+ * Component: Version Badge
+ * Documentation: documentation/frontend/components.md
+ */
+
+'use client';
+
+import React, { useEffect, useState } from 'react';
+
+export function VersionBadge() {
+  const [version, setVersion] = useState<string | null>(null);
+
+  useEffect(() => {
+    // Try to get version from build-time env var first (instant, no API call)
+    const buildTimeVersion = process.env.NEXT_PUBLIC_GIT_COMMIT;
+
+    if (buildTimeVersion && buildTimeVersion !== 'unknown') {
+      // Get short commit hash (first 7 characters)
+      const shortCommit = buildTimeVersion.length >= 7
+        ? buildTimeVersion.substring(0, 7)
+        : buildTimeVersion;
+      setVersion(`v.${shortCommit}`);
+    } else {
+      // Fallback to API call if build-time env var is not available
+      fetch('/api/version')
+        .then((res) => res.json())
+        .then((data) => {
+          setVersion(data.version);
+        })
+        .catch((error) => {
+          console.error('Failed to fetch version:', error);
+          setVersion('v.dev');
+        });
+    }
+  }, []);
+
+  if (!version) {
+    return null;
+  }
+
+  return (
+    <div
+      className="inline-flex items-center px-2.5 py-1 rounded-md bg-gradient-to-r from-gray-100 to-gray-200 dark:from-gray-700 dark:to-gray-800 border border-gray-300 dark:border-gray-600 shadow-sm"
+      title={`Version ${version}`}
+    >
+      <span className="text-xs font-mono font-medium text-gray-700 dark:text-gray-300">
+        {version}
+      </span>
+    </div>
+  );
+}