refactor: migrate to modular tool-based architecture

- Implement tool registry system with individual tool modules
- Reorganize transformers into categorized source modules
- Remove emojiLibrary.js, consolidate into EmojiUtils and emojiData
- Fix mobile close button and tooltip functionality
- Add build system for transforms and emoji data
- Migrate from Python backend to pure JavaScript
- Add comprehensive documentation and testing
- Improve code organization and maintainability
- Ignore generated files (transforms-bundle.js, emojiData.js)

js/utils/notifications.js

@@ -0,0 +1,37 @@
+window.NotificationUtils = {
+    showNotification(message, type = 'success', iconClass = null) {
+        const existing = document.querySelector('.copy-notification');
+        if (existing) {
+            existing.remove();
+        }
+        
+        const notification = document.createElement('div');
+        notification.className = `copy-notification ${type || 'success'}`;
+        
+        if (iconClass) {
+            const icon = document.createElement('i');
+            icon.className = iconClass;
+            notification.appendChild(icon);
+        }
+        
+        const text = document.createElement('span');
+        text.textContent = message;
+        notification.appendChild(text);
+        
+        document.body.appendChild(notification);
+        
+        setTimeout(() => {
+            notification.classList.add('fade-out');
+            setTimeout(() => {
+                if (notification.parentNode) {
+                    notification.parentNode.removeChild(notification);
+                }
+            }, 300);
+        }, 3000);
+    },
+    
+    showCopiedPopup() {
+        this.showNotification('Copied!', 'success', 'fas fa-check');
+    }
+};
+