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/npm-package-json-lint/dist/src/native-rules.d.ts

@@ -0,0 +1,37 @@
+import { LintFunction } from './types/lint-function';
+import { RuleType } from './types/rule-type';
+export interface Rule {
+    lint: LintFunction;
+    ruleType: RuleType;
+    minItems?: number;
+}
+export declare class Rules {
+    rules: Record<string, string>;
+    constructor();
+    /**
+     * Loads rules
+     *
+     * @return Set of rules
+     */
+    load(): Record<string, string>;
+    /**
+     * Loads a rule module
+     *
+     * @param ruleId Name of the rule
+     * @return Rule module
+     */
+    get(ruleId: string): Rule;
+    /**
+     * Gets entire rule set
+     *
+     * @returns Rule set
+     */
+    getRules(): Record<string, string>;
+    /**
+     * Registers a rule in the rules object
+     *
+     * @param ruleId Name of the rule
+     * @param filePathToRuleModule File path to rule
+     */
+    registerRule(ruleId: string, filePathToRuleModule: string): void;
+}