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/eslint/messages/all-files-ignored.js

@@ -0,0 +1,16 @@
+"use strict";
+
+module.exports = function(it) {
+    const { pattern } = it;
+
+    return `
+You are linting "${pattern}", but all of the files matching the glob pattern "${pattern}" are ignored.
+
+If you don't want to lint these files, remove the pattern "${pattern}" from the list of arguments passed to ESLint.
+
+If you do want to lint these files, try the following solutions:
+
+* Check your .eslintignore file, or the eslintIgnore property in package.json, to ensure that the files are not configured to be ignored.
+* Explicitly list the files from this glob that you'd like to lint on the command-line, rather than providing a glob as an argument.
+`.trimStart();
+};