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/framer-motion/dist/es/render/utils/resolve-variants.mjs

@@ -0,0 +1,26 @@
+function resolveVariantFromProps(props, definition, custom, currentValues = {}, currentVelocity = {}) {
+    /**
+     * If the variant definition is a function, resolve.
+     */
+    if (typeof definition === "function") {
+        definition = definition(custom !== undefined ? custom : props.custom, currentValues, currentVelocity);
+    }
+    /**
+     * If the variant definition is a variant label, or
+     * the function returned a variant label, resolve.
+     */
+    if (typeof definition === "string") {
+        definition = props.variants && props.variants[definition];
+    }
+    /**
+     * At this point we've resolved both functions and variant labels,
+     * but the resolved variant label might itself have been a function.
+     * If so, resolve. This can only have returned a valid target object.
+     */
+    if (typeof definition === "function") {
+        definition = definition(custom !== undefined ? custom : props.custom, currentValues, currentVelocity);
+    }
+    return definition;
+}
+
+export { resolveVariantFromProps };