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/autoprefixer/lib/hacks/image-rendering.js

@@ -0,0 +1,48 @@
+let Declaration = require('../declaration')
+
+class ImageRendering extends Declaration {
+  /**
+   * Add hack only for crisp-edges
+   */
+  check(decl) {
+    return decl.value === 'pixelated'
+  }
+
+  /**
+   * Return property name by spec
+   */
+  normalize() {
+    return 'image-rendering'
+  }
+
+  /**
+   * Change property name for IE
+   */
+  prefixed(prop, prefix) {
+    if (prefix === '-ms-') {
+      return '-ms-interpolation-mode'
+    }
+    return super.prefixed(prop, prefix)
+  }
+
+  /**
+   * Warn on old value
+   */
+  process(node, result) {
+    return super.process(node, result)
+  }
+
+  /**
+   * Change property and value for IE
+   */
+  set(decl, prefix) {
+    if (prefix !== '-ms-') return super.set(decl, prefix)
+    decl.prop = '-ms-interpolation-mode'
+    decl.value = 'nearest-neighbor'
+    return decl
+  }
+}
+
+ImageRendering.names = ['image-rendering', 'interpolation-mode']
+
+module.exports = ImageRendering