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/postcss-modules-values/src/index.js

@@ -0,0 +1,142 @@
+"use strict";
+
+const ICSSUtils = require("icss-utils");
+
+const matchImports = /^(.+?|\([\s\S]+?\))\s+from\s+("[^"]*"|'[^']*'|[\w-]+)$/;
+const matchValueDefinition = /(?:\s+|^)([\w-]+):?(.*?)$/;
+const matchImport = /^([\w-]+)(?:\s+as\s+([\w-]+))?/;
+
+module.exports = (options) => {
+  let importIndex = 0;
+  const createImportedName =
+    (options && options.createImportedName) ||
+    ((importName /*, path*/) =>
+      `i__const_${importName.replace(/\W/g, "_")}_${importIndex++}`);
+
+  return {
+    postcssPlugin: "postcss-modules-values",
+    prepare(result) {
+      const importAliases = [];
+      const definitions = {};
+
+      return {
+        Once(root, postcss) {
+          root.walkAtRules(/value/i, (atRule) => {
+            const matches = atRule.params.match(matchImports);
+
+            if (matches) {
+              let [, /*match*/ aliases, path] = matches;
+
+              // We can use constants for path names
+              if (definitions[path]) {
+                path = definitions[path];
+              }
+
+              const imports = aliases
+                .replace(/^\(\s*([\s\S]+)\s*\)$/, "$1")
+                .split(/\s*,\s*/)
+                .map((alias) => {
+                  const tokens = matchImport.exec(alias);
+
+                  if (tokens) {
+                    const [, /*match*/ theirName, myName = theirName] = tokens;
+                    const importedName = createImportedName(myName);
+                    definitions[myName] = importedName;
+                    return { theirName, importedName };
+                  } else {
+                    throw new Error(`@import statement "${alias}" is invalid!`);
+                  }
+                });
+
+              importAliases.push({ path, imports });
+
+              atRule.remove();
+
+              return;
+            }
+
+            if (atRule.params.indexOf("@value") !== -1) {
+              result.warn("Invalid value definition: " + atRule.params);
+            }
+
+            let [, key, value] = `${atRule.params}${atRule.raws.between}`.match(
+              matchValueDefinition
+            );
+
+            const normalizedValue = value.replace(/\/\*((?!\*\/).*?)\*\//g, "");
+
+            if (normalizedValue.length === 0) {
+              result.warn("Invalid value definition: " + atRule.params);
+              atRule.remove();
+
+              return;
+            }
+
+            let isOnlySpace = /^\s+$/.test(normalizedValue);
+
+            if (!isOnlySpace) {
+              value = value.trim();
+            }
+
+            // Add to the definitions, knowing that values can refer to each other
+            definitions[key] = ICSSUtils.replaceValueSymbols(
+              value,
+              definitions
+            );
+
+            atRule.remove();
+          });
+
+          /* If we have no definitions, don't continue */
+          if (!Object.keys(definitions).length) {
+            return;
+          }
+
+          /* Perform replacements */
+          ICSSUtils.replaceSymbols(root, definitions);
+
+          /* We want to export anything defined by now, but don't add it to the CSS yet or it well get picked up by the replacement stuff */
+          const exportDeclarations = Object.keys(definitions).map((key) =>
+            postcss.decl({
+              value: definitions[key],
+              prop: key,
+              raws: { before: "\n  " },
+            })
+          );
+
+          /* Add export rules if any */
+          if (exportDeclarations.length > 0) {
+            const exportRule = postcss.rule({
+              selector: ":export",
+              raws: { after: "\n" },
+            });
+
+            exportRule.append(exportDeclarations);
+
+            root.prepend(exportRule);
+          }
+
+          /* Add import rules */
+          importAliases.reverse().forEach(({ path, imports }) => {
+            const importRule = postcss.rule({
+              selector: `:import(${path})`,
+              raws: { after: "\n" },
+            });
+
+            imports.forEach(({ theirName, importedName }) => {
+              importRule.append({
+                value: theirName,
+                prop: importedName,
+                raws: { before: "\n  " },
+              });
+            });
+
+            root.prepend(importRule);
+          });
+        },
+      };
+    },
+  };
+};
+
+module.exports.postcss = true;