fix: prevent asset conflicts between React and Grid.js versions

Add coexistence checks to all enqueue methods to prevent loading
both React and Grid.js assets simultaneously.

Changes:
- ReactAdmin.php: Only enqueue React assets when ?react=1
- Init.php: Skip Grid.js when React active on admin pages
- Form.php, Coupon.php, Access.php: Restore classic assets when ?react=0
- Customer.php, Product.php, License.php: Add coexistence checks

Now the toggle between Classic and React versions works correctly.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

node_modules/yargs/build/lib/utils/levenshtein.js

@@ -0,0 +1,34 @@
+export function levenshtein(a, b) {
+    if (a.length === 0)
+        return b.length;
+    if (b.length === 0)
+        return a.length;
+    const matrix = [];
+    let i;
+    for (i = 0; i <= b.length; i++) {
+        matrix[i] = [i];
+    }
+    let j;
+    for (j = 0; j <= a.length; j++) {
+        matrix[0][j] = j;
+    }
+    for (i = 1; i <= b.length; i++) {
+        for (j = 1; j <= a.length; j++) {
+            if (b.charAt(i - 1) === a.charAt(j - 1)) {
+                matrix[i][j] = matrix[i - 1][j - 1];
+            }
+            else {
+                if (i > 1 &&
+                    j > 1 &&
+                    b.charAt(i - 2) === a.charAt(j - 1) &&
+                    b.charAt(i - 1) === a.charAt(j - 2)) {
+                    matrix[i][j] = matrix[i - 2][j - 2] + 1;
+                }
+                else {
+                    matrix[i][j] = Math.min(matrix[i - 1][j - 1] + 1, Math.min(matrix[i][j - 1] + 1, matrix[i - 1][j] + 1));
+                }
+            }
+        }
+    }
+    return matrix[b.length][a.length];
+}