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/@bcoe/v8-coverage/dist/lib/range-tree.d.ts

@@ -0,0 +1,24 @@
+import { RangeCov } from "./types";
+export declare class RangeTree {
+    start: number;
+    end: number;
+    delta: number;
+    children: RangeTree[];
+    constructor(start: number, end: number, delta: number, children: RangeTree[]);
+    /**
+     * @precodition `ranges` are well-formed and pre-order sorted
+     */
+    static fromSortedRanges(ranges: ReadonlyArray<RangeCov>): RangeTree | undefined;
+    normalize(): void;
+    /**
+     * @precondition `tree.start < value && value < tree.end`
+     * @return RangeTree Right part
+     */
+    split(value: number): RangeTree;
+    /**
+     * Get the range coverages corresponding to the tree.
+     *
+     * The ranges are pre-order sorted.
+     */
+    toRanges(): RangeCov[];
+}