feat: complete Simple Mode contextual routing and navigation state synchronization

lib/core/widgets/tool_card.dart

@@ -0,0 +1,69 @@
+import 'package:flutter/material.dart';
+import '../../app/theme/app_colors.dart';
+
+class ToolCard extends StatelessWidget {
+  final IconData icon;
+  final String title;
+  final Color color;
+  final bool isDark;
+  final VoidCallback onTap;
+
+  const ToolCard({
+    super.key,
+    required this.icon,
+    required this.title,
+    required this.color,
+    required this.isDark,
+    required this.onTap,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTap: onTap,
+      child: Container(
+        height: 140,
+        padding: const EdgeInsets.all(16),
+        decoration: BoxDecoration(
+          color: isDark ? AppColors.surfaceDark : AppColors.surfaceLight,
+          borderRadius: BorderRadius.circular(20),
+          border: Border.all(
+            color: isDark
+                ? color.withValues(alpha: 0.15)
+                : AppColors.cream,
+          ),
+          boxShadow: [
+            BoxShadow(
+              color: color.withValues(alpha: 0.08),
+              blurRadius: 12,
+              offset: const Offset(0, 4),
+            ),
+          ],
+        ),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          mainAxisAlignment: MainAxisAlignment.spaceBetween,
+          children: [
+            Container(
+              width: 44,
+              height: 44,
+              decoration: BoxDecoration(
+                color: color.withValues(alpha: 0.15),
+                borderRadius: BorderRadius.circular(12),
+              ),
+              child: Icon(icon, color: color, size: 24),
+            ),
+            Text(
+              title,
+              style: const TextStyle(
+                fontSize: 15,
+                fontWeight: FontWeight.w700,
+                height: 1.3,
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}