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/usage.d.ts

@@ -0,0 +1,30 @@
+import * as ts from 'typescript';
+export interface VariableInfo {
+    domain: DeclarationDomain;
+    exported: boolean;
+    uses: VariableUse[];
+    inGlobalScope: boolean;
+    declarations: ts.Identifier[];
+}
+export interface VariableUse {
+    domain: UsageDomain;
+    location: ts.Identifier;
+}
+export declare enum DeclarationDomain {
+    Namespace = 1,
+    Type = 2,
+    Value = 4,
+    Import = 8,
+    Any = 7
+}
+export declare enum UsageDomain {
+    Namespace = 1,
+    Type = 2,
+    Value = 4,
+    ValueOrNamespace = 5,
+    Any = 7,
+    TypeQuery = 8
+}
+export declare function getUsageDomain(node: ts.Identifier): UsageDomain | undefined;
+export declare function getDeclarationDomain(node: ts.Identifier): DeclarationDomain | undefined;
+export declare function collectVariableUsage(sourceFile: ts.SourceFile): Map<ts.Identifier, VariableInfo>;