refactor: deduplicate & other code quality fixes

lib/models/plex_hub.dart

@@ -23,9 +23,10 @@ class PlexHub {
   factory PlexHub.fromJson(Map<String, dynamic> json) {
     final metadataList = <PlexMetadata>[];
 
-    // Hubs can contain either Metadata or Directory entries
-    if (json['Metadata'] != null) {
-      for (final item in json['Metadata'] as List) {
+    // Helper function to parse entries from a JSON list
+    void parseEntries(List? entries) {
+      if (entries == null) return;
+      for (final item in entries) {
         try {
           metadataList.add(PlexMetadata.fromJson(item));
         } catch (e) {
@@ -34,15 +35,9 @@ class PlexHub {
       }
     }
 
-    if (json['Directory'] != null) {
-      for (final item in json['Directory'] as List) {
-        try {
-          metadataList.add(PlexMetadata.fromJson(item));
-        } catch (e) {
-          // Skip items that fail to parse
-        }
-      }
-    }
+    // Hubs can contain either Metadata or Directory entries
+    parseEntries(json['Metadata'] as List?);
+    parseEntries(json['Directory'] as List?);
 
     return PlexHub(
       hubKey: json['key'] as String? ?? '',