add macOS support for ad loading and improve timestamp handling

lib/services/quote_api_v2.dart

@@ -159,9 +159,36 @@ class QuoteSession {
 }
 
 
+class QuoteSnapshot {
+  final String token;
+  final String url;
+  final String sessionId;
+  final int createdAt;
+  final int expiresAt;
+
+  QuoteSnapshot({
+    required this.token,
+    required this.url,
+    required this.sessionId,
+    required this.createdAt,
+    required this.expiresAt,
+  });
+
+  factory QuoteSnapshot.fromJson(Map<String, dynamic> json) {
+    return QuoteSnapshot(
+      token: json["token"],
+      url: json["url"],
+      sessionId: json["sessionId"],
+      createdAt: json["createdAt"],
+      expiresAt: json["expiresAt"],
+    );
+  }
+}
+
+
 class QuoteGeneratorApiV2 {
-  static const String _baseUrl = "https://quotes.imbenji.net";
-  // static const String _baseUrl = "http://localhost:3000";
+  // static const String _baseUrl = "https://quotes.imbenji.net";
+  static const String _baseUrl = "http://localhost:3000";
 
 
   // create new session
@@ -259,6 +286,40 @@ class QuoteGeneratorApiV2 {
   }
 
 
+  // create persistant snapshot link
+  static Future<QuoteSnapshot> createSnapshotLink(String sessionId) async {
+    final url = Uri.parse("$_baseUrl/v2/quote/$sessionId/snapshot-link");
+
+    final response = await http.post(
+      url,
+      headers: {"User-Agent": "QuoteGen-Flutter/1.0"},
+    );
+
+    if (response.statusCode == 201) {
+      final data = jsonDecode(response.body);
+      return QuoteSnapshot.fromJson(data);
+    } else {
+      throw Exception("Failed to create snapshot link: ${response.statusCode}");
+    }
+  }
+
+  // get snapshot image by token
+  static Future<Uint8List> getSnapshot(String token) async {
+    final url = Uri.parse("$_baseUrl/v2/snapshot/$token");
+
+    final response = await http.get(
+      url,
+      headers: {"User-Agent": "QuoteGen-Flutter/1.0"},
+    );
+
+    if (response.statusCode == 200) {
+      return response.bodyBytes;
+    } else {
+      throw Exception("Failed to get snapshot: ${response.statusCode}");
+    }
+  }
+
+
   // helper to get current timestamp in seconds
   static int getCurrentTimestamp() {
     return DateTime.now().millisecondsSinceEpoch ~/ 1000;