Rebuild Noo as a full Nextcloud client: auth, media, and Material You UI

Replaces the starter template with Login Flow v2 auth, WebDAV-backed
Files/Photos/Activity tabs, a swipeable media viewer with PDF/text/video
preview, Material You dynamic theming, a frosted-glass floating nav bar,
and a rebranded app icon/identity (com.example -> family.nasa).

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

lib/models/nextcloud_item.dart

@@ -9,12 +9,14 @@ class NextcloudItem {
   final NextcloudItemType type;
   final int size; // in bytes
   final DateTime lastModified;
+  final DateTime dateCreated;
   final bool isFavorite;
   final String? mimeType;
   final String? etag;
   final String? previewUrl;
   final int? imageWidth;
   final int? imageHeight;
+  final String? mountType;
 
   const NextcloudItem({
     required this.id,
@@ -23,16 +25,20 @@ class NextcloudItem {
     required this.type,
     required this.size,
     required this.lastModified,
+    DateTime? dateCreated,
     this.isFavorite = false,
     this.mimeType,
     this.etag,
     this.previewUrl,
     this.imageWidth,
     this.imageHeight,
-  });
+    this.mountType,
+  }) : dateCreated = dateCreated ?? lastModified;
 
   bool get isFolder => type == NextcloudItemType.folder;
-  bool get isMedia => type == NextcloudItemType.image || type == NextcloudItemType.video;
+  bool get isMedia =>
+      type == NextcloudItemType.image || type == NextcloudItemType.video;
+  bool get isExternalStorage => mountType == 'external';
 
   NextcloudItem copyWith({
     String? id,
@@ -41,12 +47,14 @@ class NextcloudItem {
     NextcloudItemType? type,
     int? size,
     DateTime? lastModified,
+    DateTime? dateCreated,
     bool? isFavorite,
     String? mimeType,
     String? etag,
     String? previewUrl,
     int? imageWidth,
     int? imageHeight,
+    String? mountType,
   }) {
     return NextcloudItem(
       id: id ?? this.id,
@@ -55,31 +63,58 @@ class NextcloudItem {
       type: type ?? this.type,
       size: size ?? this.size,
       lastModified: lastModified ?? this.lastModified,
+      dateCreated: dateCreated ?? this.dateCreated,
       isFavorite: isFavorite ?? this.isFavorite,
       mimeType: mimeType ?? this.mimeType,
       etag: etag ?? this.etag,
       previewUrl: previewUrl ?? this.previewUrl,
       imageWidth: imageWidth ?? this.imageWidth,
       imageHeight: imageHeight ?? this.imageHeight,
+      mountType: mountType ?? this.mountType,
     );
   }
 
-  static NextcloudItemType deduceType(String path, bool isCollection, String? mime) {
+  static NextcloudItemType deduceType(
+    String path,
+    bool isCollection,
+    String? mime,
+  ) {
     if (isCollection) return NextcloudItemType.folder;
     final lower = path.toLowerCase();
-    if (mime?.startsWith('image/') == true || lower.endsWith('.jpg') || lower.endsWith('.jpeg') || lower.endsWith('.png') || lower.endsWith('.webp') || lower.endsWith('.gif') || lower.endsWith('.heic')) {
+    if (mime?.startsWith('image/') == true ||
+        lower.endsWith('.jpg') ||
+        lower.endsWith('.jpeg') ||
+        lower.endsWith('.png') ||
+        lower.endsWith('.webp') ||
+        lower.endsWith('.gif') ||
+        lower.endsWith('.heic')) {
       return NextcloudItemType.image;
     }
-    if (mime?.startsWith('video/') == true || lower.endsWith('.mp4') || lower.endsWith('.mov') || lower.endsWith('.mkv') || lower.endsWith('.webm')) {
+    if (mime?.startsWith('video/') == true ||
+        lower.endsWith('.mp4') ||
+        lower.endsWith('.mov') ||
+        lower.endsWith('.mkv') ||
+        lower.endsWith('.webm')) {
       return NextcloudItemType.video;
     }
-    if (mime?.startsWith('audio/') == true || lower.endsWith('.mp3') || lower.endsWith('.flac') || lower.endsWith('.wav') || lower.endsWith('.ogg')) {
+    if (mime?.startsWith('audio/') == true ||
+        lower.endsWith('.mp3') ||
+        lower.endsWith('.flac') ||
+        lower.endsWith('.wav') ||
+        lower.endsWith('.ogg')) {
       return NextcloudItemType.audio;
     }
-    if (lower.endsWith('.pdf') || lower.endsWith('.txt') || lower.endsWith('.md') || lower.endsWith('.docx') || lower.endsWith('.xlsx')) {
+    if (lower.endsWith('.pdf') ||
+        lower.endsWith('.txt') ||
+        lower.endsWith('.md') ||
+        lower.endsWith('.docx') ||
+        lower.endsWith('.xlsx')) {
       return NextcloudItemType.document;
     }
-    if (lower.endsWith('.zip') || lower.endsWith('.tar') || lower.endsWith('.gz') || lower.endsWith('.7z')) {
+    if (lower.endsWith('.zip') ||
+        lower.endsWith('.tar') ||
+        lower.endsWith('.gz') ||
+        lower.endsWith('.7z')) {
       return NextcloudItemType.archive;
     }
     return NextcloudItemType.file;