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/base62.js

@@ -0,0 +1,44 @@
+// base62 transform
+import BaseTransformer from '../BaseTransformer.js';
+
+export default new BaseTransformer({
+
+        name: 'Base62',
+    priority: 290,
+    alphabet: '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz',
+        func: function(text) {
+            if (!text) return '';
+            const bytes = new TextEncoder().encode(text);
+            let n = 0n;
+            for (let b of bytes) { n = (n << 8n) + BigInt(b); }
+            if (n === 0n) return '0';
+            let out = '';
+            while (n > 0n) {
+                const rem = n % 62n;
+                n = n / 62n;
+                out = this.alphabet[Number(rem)] + out;
+            }
+            return out;
+        },
+        preview: function(text) {
+            if (!text) return '[base62]';
+            return this.func(text.slice(0, 3)) + '...';
+        },
+        reverse: function(text) {
+            if (!text) return '';
+            let n = 0n;
+            for (let c of text) {
+                const i = this.alphabet.indexOf(c);
+                if (i < 0) continue;
+                n = n * 62n + BigInt(i);
+            }
+            const bytes = [];
+            while (n > 0n) {
+                bytes.unshift(Number(n % 256n));
+                n = n / 256n;
+            }
+            if (bytes.length === 0) bytes.push(0);
+            return new TextDecoder().decode(Uint8Array.from(bytes));
+        }
+
+});