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/remove-accents/test.js

@@ -0,0 +1,47 @@
+var removeAccents = require("./");
+
+test("remove accents from string", function () {
+	var input =
+		"ÀÁÂÃÄÅẤẮÆẦẰẢẠẨẪẬÇḈÈÉÊËẾḖỀḔẺẼẸỂỄỆÌÍÎÏḮỈỊÐÑÒÓÔÕÖØỐṌṒỎỌỔỖỘỜỞỠỚỢÙÚÛÜỦỤỬỮỰÝàáâãäåấắæầằảạẩẫậçḉèéêëếḗềḕẻẽẹểễệìíîïḯỉịñòóôõöøốṍṓỏọổỗộờởỡớợùúûüủụửữựýÿĀāĂ㥹ĆćĈĉĊċČčĎďĐđĒēĔĕĖėĘęĚěĜĝĞğĠġĢģǴǵĤĥĦħĨĩĪīĬĭĮįİıIJijĴĵĶķḰḱĹĺĻļĽľĿŀŁłḾḿŃńŅņŇňʼnŌōŎŏŐőŒœŔŕŖŗŘřŚśŜŝŞşŠšŢţŤťŦŧŨũŪūŬŭŮůŰűŲųŴŵẂẃŶŷŸŹźŻżŽžſƒƠơƯưǍǎǏǐǑǒǓǔǕǖǗǘǙǚǛǜỨứṸṹǺǻǼǽǾǿðÞþṔṕṤṥX́x́ЃѓЌќA̋a̋E̋e̋I̋i̋ǸǹỒồṐṑỪừẀẁỲỳȀȁȄȅȈȉȌȍȐȑȔȕẲẴẶḜẳẵặḝC̆c̆ḪḫK̆k̆M̆m̆N̆n̆P̆p̆R̆r̆T̆t̆V̆v̆X̆x̆Y̆y̆ȂȆȊȎȃȇȋȏȒȓȖȗșțȘȚB̌b̌F̌f̌ǦǧȞȟJ̌ǰǨǩM̌m̌P̌p̌Q̌q̌ṦṧV̌v̌W̌w̌X̌x̌Y̌y̌A̧a̧B̧b̧ḐḑȨȩƐ̧ɛ̧ḨḩI̧i̧Ɨ̧ɨ̧M̧m̧O̧o̧Q̧q̧U̧u̧X̧x̧Z̧z";
+	var output = removeAccents(input);
+	var expected =
+		"AAAAAAAAAEAAAAAAACCEEEEEEEEEEEEEEIIIIIIIDNOOOOOOOOOOOOOOOOOOOUUUUUUUUUYaaaaaaaaaeaaaaaaacceeeeeeeeeeeeeeiiiiiiinooooooooooooooooooouuuuuuuuuyyAaAaAaCcCcCcCcDdDdEeEeEeEeEeGgGgGgGgGgHhHhIiIiIiIiIiIJijJjKkKkLlLlLlLlllMmNnNnNnnOoOoOoOEoeRrRrRrSsSsSsSsTtTtTtUuUuUuUuUuUuWwWwYyYZzZzZzsfOoUuAaIiOoUuUuUuUuUuUuUuAaAEaeOodTHthPpSsXxГгКкAaEeIiNnOoOoUuWwYyAaEeIiOoRrUuAAAEaaaeCcHhKkMmNnPpRrTtVvXxYyAEIOaeioRrUustSTBbFfGgHhJjKkMmPpQqSsVvWwXxYyAaBbDdEeEeHhIiIiMmOoQqUuXxZz";
+
+	expect(output).toBe(expected);
+});
+
+test("remove cyrillic accents from string", function () {
+	var input = "ЁёЙй";
+	var output = removeAccents(input);
+	var expected = "ЕеИи";
+
+	expect(output).toBe(expected);
+});
+
+test("do not modify non-accented strings", function () {
+	var input =
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz123456789.,:;~`!@#$%^&*()-_=+[]{}'\"|\\<>?/eEиИ";
+	var output = removeAccents(input);
+
+	expect(output).toBe(input);
+});
+
+test(".has can detect accents", function () {
+	expect(removeAccents.has("À")).toBe(true);
+	expect(removeAccents.has("Löwe")).toBe(true);
+
+	expect(removeAccents.has("A")).toBe(false);
+	expect(removeAccents.has("Panther")).toBe(false);
+});
+
+test(".remove method", function () {
+	expect(removeAccents.toString()).toBe(removeAccents.remove.toString());
+
+	expect(removeAccents.remove("cat")).toBe("cat");
+	expect(removeAccents.remove("Pokémon")).toBe("Pokemon");
+});
+
+// See https://github.com/tyxla/remove-accents/issues/12
+test("ß is not accented", function () {
+	expect(removeAccents.remove("Straße")).toBe("Straße");
+});