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/tsutils/util/control-flow.d.ts

@@ -0,0 +1,24 @@
+import * as ts from 'typescript';
+export declare function endsControlFlow(statement: ts.Statement | ts.BlockLike, checker?: ts.TypeChecker): boolean;
+export declare type ControlFlowStatement = ts.BreakStatement | ts.ContinueStatement | ts.ReturnStatement | ts.ThrowStatement | ts.ExpressionStatement & {
+    expression: ts.CallExpression;
+};
+export interface ControlFlowEnd {
+    /**
+     * Statements that may end control flow at this statement.
+     * Does not contain control flow statements that jump only inside the statement, for example a `continue` inside a nested for loop.
+     */
+    readonly statements: ReadonlyArray<ControlFlowStatement>;
+    /** `true` if control flow definitely ends. */
+    readonly end: boolean;
+}
+export declare function getControlFlowEnd(statement: ts.Statement | ts.BlockLike, checker?: ts.TypeChecker): ControlFlowEnd;
+export declare enum SignatureEffect {
+    Never = 1,
+    Asserts = 2
+}
+/**
+ * Dermines whether a top level CallExpression has a control flow effect according to TypeScript's rules.
+ * This handles functions returning `never` and `asserts`.
+ */
+export declare function callExpressionAffectsControlFlow(node: ts.CallExpression, checker: ts.TypeChecker): SignatureEffect | undefined;