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)

src/transformers/encoding/invisible-text.js

@@ -0,0 +1,39 @@
+// invisible-text transform
+import BaseTransformer from '../BaseTransformer.js';
+
+export default new BaseTransformer({
+
+        name: 'Invisible Text',
+    priority: 100, // High confidence - uses exclusive Unicode Private Use Area (U+E0000-U+E00FF)
+    func: function(text) {
+            if (!text) return '';
+            const bytes = new TextEncoder().encode(text);
+            return Array.from(bytes)
+                .map(byte => String.fromCodePoint(0xE0000 + byte))
+                .join('');
+        },
+        preview: function(text) {
+            return '[invisible]';
+        },
+        reverse: function(text) {
+            if (!text) return '';
+            const matches = [...text.matchAll(/[\u{E0000}-\u{E00FF}]/gu)];
+            if (!matches.length) return '';
+            
+            // Convert invisible characters back to bytes
+            const bytes = new Uint8Array(
+                matches.map(match => match[0].codePointAt(0) - 0xE0000)
+            );
+            
+            // Use TextDecoder to properly handle UTF-8 encoded bytes (including emoji)
+            return new TextDecoder().decode(bytes);
+        },
+        // Detector: Check for at least one invisible Unicode character
+        detector: function(text) {
+            // Invisible text uses Unicode Private Use Area (U+E0000-U+E00FF for full byte range)
+            const invisibleMatches = text.match(/[\u{E0000}-\u{E00FF}]/gu);
+            // Return true if at least one invisible character is found
+            return invisibleMatches && invisibleMatches.length > 0;
+        }
+
+});