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/config/features.js

@@ -0,0 +1,81 @@
+/**
+ * Feature Toggle System
+ * 
+ * Controls which features are available in FREE vs PRO versions
+ * Currently static, will be dynamic from database in the future
+ */
+
+// User tier - will be fetched from database/auth in the future
+export const USER_TIER = {
+  FREE: 'free',
+  PRO: 'pro'
+};
+
+// Current user tier (static for now, will be dynamic)
+// TODO: Replace with actual user tier from authentication/database
+export const getCurrentUserTier = () => {
+  // For development/testing, you can change this
+  const staticTier = USER_TIER.PRO; // Change to USER_TIER.PRO to test pro features
+  
+  // In the future, this will be:
+  // return getUserFromAuth()?.tier || USER_TIER.FREE;
+  
+  return staticTier;
+};
+
+// Feature flags
+export const FEATURES = {
+  // Advanced URL Fetch with headers, methods, body, auth
+  ADVANCED_URL_FETCH: {
+    name: 'Advanced URL Fetch',
+    description: 'Custom HTTP methods, headers, authentication, and request body',
+    tier: USER_TIER.PRO,
+    enabled: (userTier) => userTier === USER_TIER.PRO
+  },
+  
+  // Future pro features can be added here
+  BULK_OPERATIONS: {
+    name: 'Bulk Operations',
+    description: 'Process multiple files or operations at once',
+    tier: USER_TIER.PRO,
+    enabled: (userTier) => userTier === USER_TIER.PRO
+  },
+  
+  EXPORT_TEMPLATES: {
+    name: 'Export Templates',
+    description: 'Save and reuse custom export templates',
+    tier: USER_TIER.PRO,
+    enabled: (userTier) => userTier === USER_TIER.PRO
+  },
+  
+  CLOUD_SYNC: {
+    name: 'Cloud Sync',
+    description: 'Sync your data and settings across devices',
+    tier: USER_TIER.PRO,
+    enabled: (userTier) => userTier === USER_TIER.PRO
+  }
+};
+
+// Helper function to check if a feature is enabled
+export const isFeatureEnabled = (featureName) => {
+  const feature = FEATURES[featureName];
+  if (!feature) return false;
+  
+  const userTier = getCurrentUserTier();
+  return feature.enabled(userTier);
+};
+
+// Helper function to get user tier
+export const getUserTier = () => {
+  return getCurrentUserTier();
+};
+
+// Helper function to check if user is pro
+export const isProUser = () => {
+  return getCurrentUserTier() === USER_TIER.PRO;
+};
+
+// Helper function to get feature info
+export const getFeatureInfo = (featureName) => {
+  return FEATURES[featureName] || null;
+};