feat: Implement expiring cache for S3 image URLs, add error retry logic, and clear image caches on app startup.

lib/core/widgets/s3_image.dart

@@ -33,6 +33,7 @@ class _S3ImageState extends State<S3Image> {
   String? _resolvedUrl;
   bool _loading = true;
   bool _failed = false;
+  bool _retried = false;
 
   @override
   void initState() {
@@ -106,13 +107,22 @@ class _S3ImageState extends State<S3Image> {
 
     return CachedNetworkImage(
       imageUrl: _resolvedUrl!,
-      cacheKey: widget.imageUrl,
+      cacheKey: widget.imageUrl ?? _resolvedUrl!,
       width: widget.width,
       height: widget.height,
       fit: widget.fit,
       alignment: widget.alignment,
       placeholder: (ctx, _) => _buildPlaceholder(ctx),
-      errorWidget: (ctx, _, _) => _buildError(ctx),
+      errorWidget: (ctx, _, err) {
+        // On error (expired URL), evict and retry once
+        if (!_retried) {
+          _retried = true;
+          ImageUrlResolver.instance.evict(widget.imageUrl);
+          _resolve();
+          return _buildPlaceholder(ctx);
+        }
+        return _buildError(ctx);
+      },
     );
   }
 }