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-plugin-jest/docs/rules/no-deprecated-functions.md

@@ -0,0 +1,57 @@
+# Disallow use of deprecated functions (`no-deprecated-functions`)
+
+💼 This rule is enabled in the ✅ `recommended`
+[config](https://github.com/jest-community/eslint-plugin-jest/blob/main/README.md#shareable-configurations).
+
+🔧 This rule is automatically fixable by the
+[`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
+
+<!-- end auto-generated rule header -->
+
+Over the years Jest has accrued some debt in the form of functions that have
+either been renamed for clarity, or replaced with more powerful APIs.
+
+While typically these deprecated functions are kept in the codebase for a number
+of majors, eventually they are removed completely.
+
+This rule requires knowing which version of Jest you're using - see
+[this section of the readme](../../README.md#jest-version-setting) for details
+on how that is obtained automatically and how you can explicitly provide a
+version if needed.
+
+## Rule details
+
+This rule warns about calls to deprecated functions, and provides details on
+what to replace them with, based on the version of Jest that is installed.
+
+This rule can also autofix a number of these deprecations for you.
+
+### `jest.resetModuleRegistry`
+
+This function was renamed to `resetModules` in Jest 15 and removed in Jest 27.
+
+### `jest.addMatchers`
+
+This function was replaced with `expect.extend` in Jest 17 and removed in
+Jest 27.
+
+### `require.requireActual` & `require.requireMock`
+
+These functions were replaced in Jest 21 and removed in Jest 26.
+
+Originally, the `requireActual` & `requireMock` the `requireActual`&
+`requireMock` functions were placed onto the `require` function.
+
+These functions were later moved onto the `jest` object in order to be easier
+for type checkers to handle, and their use via `require` deprecated. Finally,
+the release of Jest 26 saw them removed from the `require` function altogether.
+
+### `jest.runTimersToTime`
+
+This function was renamed to `advanceTimersByTime` in Jest 22 and removed in
+Jest 27.
+
+### `jest.genMockFromModule`
+
+This function was renamed to `createMockFromModule` in Jest 26, and is scheduled
+for removal in Jest 30.