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/typings/common-types.js

@@ -0,0 +1,9 @@
+export function assertNotStrictEqual(actual, expected, shim, message) {
+    shim.assert.notStrictEqual(actual, expected, message);
+}
+export function assertSingleKey(actual, shim) {
+    shim.assert.strictEqual(typeof actual, 'string');
+}
+export function objectKeys(object) {
+    return Object.keys(object);
+}

node_modules/yargs/build/lib/typings/yargs-parser-types.js

@@ -0,0 +1 @@
+export {};