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/lodash/string.js

@@ -0,0 +1,33 @@
+module.exports = {
+  'camelCase': require('./camelCase'),
+  'capitalize': require('./capitalize'),
+  'deburr': require('./deburr'),
+  'endsWith': require('./endsWith'),
+  'escape': require('./escape'),
+  'escapeRegExp': require('./escapeRegExp'),
+  'kebabCase': require('./kebabCase'),
+  'lowerCase': require('./lowerCase'),
+  'lowerFirst': require('./lowerFirst'),
+  'pad': require('./pad'),
+  'padEnd': require('./padEnd'),
+  'padStart': require('./padStart'),
+  'parseInt': require('./parseInt'),
+  'repeat': require('./repeat'),
+  'replace': require('./replace'),
+  'snakeCase': require('./snakeCase'),
+  'split': require('./split'),
+  'startCase': require('./startCase'),
+  'startsWith': require('./startsWith'),
+  'template': require('./template'),
+  'templateSettings': require('./templateSettings'),
+  'toLower': require('./toLower'),
+  'toUpper': require('./toUpper'),
+  'trim': require('./trim'),
+  'trimEnd': require('./trimEnd'),
+  'trimStart': require('./trimStart'),
+  'truncate': require('./truncate'),
+  'unescape': require('./unescape'),
+  'upperCase': require('./upperCase'),
+  'upperFirst': require('./upperFirst'),
+  'words': require('./words')
+};