feat: major update - Markdown Editor, CodeMirror upgrades, SEO improvements, tool cleanup

- Added new Markdown Editor with live preview, GFM support, PDF/HTML/DOCX export
- Upgraded all paste fields to CodeMirror with syntax highlighting and expand/collapse
- Enhanced Object Editor with advanced URL fetching and preview mode
- Improved export views with syntax highlighting in Table/Object editors
- Implemented SEO improvements (FAQ schema, breadcrumbs, internal linking)
- Added Related Tools recommendations component
- Created custom 404 page with tool suggestions
- Consolidated tools: removed JSON, Serialize, CSV-JSON (merged into main editors)
- Updated documentation and cleaned up redundant files
- Updated release notes with user-centric improvements

src/index.css

@@ -8,6 +8,8 @@
   html {
     font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
     overflow-x: hidden;
+    width: 100%;
+    max-width: 100vw;
   }
   
   body {
@@ -16,6 +18,13 @@
     max-width: 100vw;
   }
   
+  #root {
+    overflow-x: hidden;
+    width: 100%;
+    max-width: 100vw;
+    min-width: 0;
+  }
+  
   code, pre {
     font-family: 'JetBrains Mono', Monaco, 'Cascadia Code', 'Segoe UI Mono', 'Roboto Mono', monospace;
   }
@@ -38,6 +47,14 @@
     @apply px-4 py-2 bg-gray-200 hover:bg-gray-300 dark:bg-gray-700 dark:hover:bg-gray-600 text-gray-700 dark:text-gray-300 rounded-md font-medium transition-colors duration-200;
   }
   
+  .tool-button-primary {
+    @apply flex items-center px-4 py-2 bg-green-600 hover:bg-green-700 text-white rounded-md font-medium transition-colors duration-200;
+  }
+  
+  .toolbar-btn {
+    @apply p-2 hover:bg-gray-200 dark:hover:bg-gray-700 rounded-md transition-colors duration-200 text-gray-700 dark:text-gray-300 font-medium text-sm;
+  }
+  
   .copy-button {
     @apply absolute top-2 right-2 p-2 bg-gray-100 hover:bg-gray-200 dark:bg-gray-700 dark:hover:bg-gray-600 rounded-md transition-colors duration-200;
   }