fix: web thumbnail loading - bypass signing on web, add fallback, improve error handling

sojorn_app/lib/services/api_service.dart

@@ -938,8 +938,15 @@ class ApiService {
   // =========================================================================
 
   Future<String> getSignedMediaUrl(String path) async {
+    // For web platform, return the original URL since signing isn't needed
+    // for public CDN domains
+    if (path.startsWith('http')) {
+      return path;
+    }
+    
     // Migrate to Go API / Nginx Signed URLs
-    return '${ApiConfig.baseUrl}/media/signed?path=$path'; // Placeholder
+    // TODO: Implement proper signed URL generation
+    return '${ApiConfig.baseUrl}/media/signed?path=$path';
   }
 
   Future<Map<String, dynamic>> toggleReaction(String postId, String emoji) async {

sojorn_app/lib/widgets/media/signed_media_image.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter/foundation.dart';
 import '../../providers/api_provider.dart';
 
 class SignedMediaImage extends ConsumerStatefulWidget {
@@ -62,6 +63,11 @@ class _SignedMediaImageState extends ConsumerState<SignedMediaImage> {
     final trimmed = url.trim();
     if (trimmed.isEmpty) return false;
 
+    // On web platform, prefer direct URLs without signing for better performance
+    if (kIsWeb) {
+      return false;
+    }
+
     final uri = Uri.tryParse(trimmed);
     if (uri == null || (!uri.hasScheme && !uri.hasAuthority)) {
       return true;
@@ -159,6 +165,15 @@ class _SignedMediaImageState extends ConsumerState<SignedMediaImage> {
         return _buildLoading(context);
       },
       errorBuilder: (context, error, stackTrace) {
+        // Debug: log the error and URL info
+        if (kDebugMode) {
+          print('SignedMediaImage error: $error');
+          print('Original URL: ${widget.url}');
+          print('Resolved URL: $_resolvedUrl');
+          print('Needs signing: $_shouldSign');
+          print('Platform: ${kIsWeb ? "web" : "native"}');
+        }
+
         if (_shouldSign && !_refreshing && !_hasRefreshed) {
           WidgetsBinding.instance.addPostFrameCallback((_) {
             if (!mounted) return;
@@ -171,6 +186,21 @@ class _SignedMediaImageState extends ConsumerState<SignedMediaImage> {
           return widget.errorBuilder!(context, error, stackTrace);
         }
 
+        // On web, try fallback to direct URL if signing failed
+        if (kIsWeb && _shouldSign && _resolvedUrl == null) {
+          return Image.network(
+            widget.url,
+            width: widget.width,
+            height: widget.height,
+            fit: widget.fit,
+            errorBuilder: widget.errorBuilder,
+            loadingBuilder: (context, child, loadingProgress) {
+              if (loadingProgress == null) return child;
+              return _buildLoading(context);
+            },
+          );
+        }
+
         return const SizedBox.shrink();
       },
     );