Refactor button component and add new sections for loading indicators, icons, and navigation; update enums and pubspec description

apps/gallery/lib/sections/fab_section.dart

@@ -0,0 +1,60 @@
+import 'package:flutter/material.dart';
+import 'package:m3e_collection/m3e_collection.dart';
+
+import 'section_card.dart';
+
+class FabSection extends StatelessWidget {
+  const FabSection({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    void onPressed() {
+      // Placeholder function onPressed
+    }
+
+    return SectionCard(
+      title: 'FabM3E',
+      subtitle:
+          'Generated from enums: kind × size. Includes Extended FAB examples.',
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Wrap(
+            spacing: 12,
+            runSpacing: 12,
+            children: [
+              for (final kind in FabM3EKind.values)
+                for (final size in FabM3ESize.values)
+                  FabM3E(
+                      icon: const Icon(Icons.add),
+                      kind: kind,
+                      size: size,
+                      onPressed: onPressed),
+            ],
+          ),
+          const SizedBox(height: 12),
+          Wrap(
+            spacing: 12,
+            runSpacing: 12,
+            children: [
+              ExtendedFabM3E(
+                  label: Text('Create'),
+                  icon: Icon(Icons.add),
+                  onPressed: onPressed),
+              ExtendedFabM3E(
+                  label: Text('Edit'),
+                  icon: Icon(Icons.edit),
+                  kind: FabM3EKind.secondary,
+                  onPressed: onPressed),
+              ExtendedFabM3E(
+                  label: Text('Share'),
+                  icon: Icon(Icons.share),
+                  kind: FabM3EKind.tertiary,
+                  onPressed: onPressed),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}