added categories, import export, settings

lib/widgets/product_image.dart

@@ -0,0 +1,80 @@
+/// Thumbnail or letter avatar for a product.
+library;
+
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+
+class ProductImage extends StatelessWidget {
+  const ProductImage({
+    super.key,
+    required this.name,
+    this.path,
+    this.size = 48,
+  });
+
+  final String name;
+  final String? path;
+  final double size;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final file = path == null ? null : File(path!);
+    final hasFile = file != null && file.existsSync();
+
+    return ClipRRect(
+      borderRadius: BorderRadius.circular(size / 4),
+      child: SizedBox(
+        width: size,
+        height: size,
+        child: hasFile
+            ? Image.file(
+                file,
+                fit: BoxFit.cover,
+                cacheWidth: (size * 3).round(),
+                errorBuilder: (_, _, _) => _LetterAvatar(
+                  name: name,
+                  size: size,
+                  colorScheme: theme.colorScheme,
+                ),
+              )
+            : _LetterAvatar(
+                name: name,
+                size: size,
+                colorScheme: theme.colorScheme,
+              ),
+      ),
+    );
+  }
+}
+
+class _LetterAvatar extends StatelessWidget {
+  const _LetterAvatar({
+    required this.name,
+    required this.size,
+    required this.colorScheme,
+  });
+
+  final String name;
+  final double size;
+  final ColorScheme colorScheme;
+
+  @override
+  Widget build(BuildContext context) {
+    final trimmed = name.trim();
+    final letter = trimmed.isEmpty ? '?' : trimmed.substring(0, 1).toUpperCase();
+    return ColoredBox(
+      color: colorScheme.secondaryContainer,
+      child: Center(
+        child: Text(
+          letter,
+          style: Theme.of(context).textTheme.titleMedium?.copyWith(
+            color: colorScheme.onSecondaryContainer,
+            fontSize: size * 0.4,
+          ),
+        ),
+      ),
+    );
+  }
+}