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/speedline-core/readme.md

@@ -0,0 +1,60 @@
+# speedline-core
+
+This is the core module for speedline, without any CLI dependencies. See [speedline](https://github.com/paulirish/speedline) for the CLI.
+
+### Install
+
+```bash
+$ npm install speedline
+```
+
+### Usage
+
+```js
+const speedline = require('speedline-core');
+
+speedline('./timeline').then(results => {
+  console.log('Speed Index value:', results.speedIndex);
+});
+```
+
+### API
+
+#### `speedline(timeline [, opts])`
+
+* (string | object[]) `timeline`
+* (object) `opts`
+
+Returns a (Promise) resolving with an object containing:
+  * `beginning` (number) - Recording start timestamp
+  * `end` (number) - Recording end timestamp
+  * `speedIndex` (number) - speed index value.
+  * `perceptualSpeedIndex` (number) - perceptual speed index value.
+  * `first` (number) - duration before the first visual change in ms.
+  * `complete` (number) - duration before the last visual change in ms.
+  * `duration` (number) - timeline recording duration in ms.
+  * `frames` ([Frame](#frame)[]) - array of all the frames extracted from the timeline.
+
+**`timeline` parameter**:
+* `string` - the parameter represents the location of the of file containing the timeline.
+* `array` - the parameter represents the traceEvents content of the timeline file.
+
+**`opts` parameter**:
+* `timeOrigin`: Provides the baseline timeStamp, typically navigationStart. Must be a monotonic clock timestamp that matches the trace.  E.g. `speedline('trace.json', {timeOrigin: 103205446186})`
+* `fastMode`: If the elapsed time and difference in similarity between two screenshots are small, fastMode will skip decoding and evaluating the frames between them.
+* `include`: Specifies which speed indexes to compute, can be one of `all|speedIndex|perceptualSpeedIndex`, defaults to `all`.
+
+#### `Frame`
+
+Object representing a single screenshot.
+
+* `frame.getHistogram()`: (number[][]) - returns the frame histogram. Note that light pixels informations are removed from the histogram, for better speed index calculation accuracy.
+* `frame.getTimeStamp()`: (number) - return the frame timestamp.
+* `frame.getImage()`: (Buffer) - return the frame content.
+* `frame.getProgress()`: (number) - return the frame visual progress.
+* `frame.getPerceptualProgress()`: (number) - return the frame perceptual visual progress.
+
+
+## License
+
+MIT © [Pierre-Marie Dartus](https://github.com/pmdartus)