Implement components + uploads flow and gateway-aligned payloads

lib/models.dart

@@ -28,7 +28,7 @@ class ChatUser {
   String? bio;
 
   // Identity
-  String publicKey; // Ed25519 public key, always stored
+  String publicKey; // ECDSA public key, always stored
 
   // HOME SERVER ONLY: Auth & key backup
   String? passwordHash;
@@ -106,6 +106,7 @@ class ChatMessage {
   String? authorAvatarUrl;
 
   String content;
+  String componentsJson;
 
   @Property(type: PropertyType.date)
   DateTime createdAt;
@@ -119,9 +120,38 @@ class ChatMessage {
     required this.authorUserId,
     required this.authorUsername,
     required this.content,
+    required this.componentsJson,
     this.authorHomeServer,
     this.authorAvatarUrl,
     DateTime? createdAt,
     this.editedAt,
   }) : createdAt = createdAt ?? DateTime.now();
 }
+
+@Entity()
+class ChatFile {
+  @Id()
+  int id = 0;
+
+  int uploaderId;
+  String path;
+  String mimeType;
+  int width;
+  int height;
+  int sizeBytes;
+  bool isAttached;
+
+  @Property(type: PropertyType.date)
+  DateTime createdAt;
+
+  ChatFile({
+    required this.uploaderId,
+    required this.path,
+    required this.mimeType,
+    required this.width,
+    required this.height,
+    required this.sizeBytes,
+    this.isAttached = false,
+    DateTime? createdAt,
+  }) : createdAt = createdAt ?? DateTime.now();
+}