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/nanoid/async/index.cjs

@@ -0,0 +1,71 @@
+let crypto = require('crypto')
+
+let { urlAlphabet } = require('../url-alphabet/index.cjs')
+
+// `crypto.randomFill()` is a little faster than `crypto.randomBytes()`,
+// because it is possible to use in combination with `Buffer.allocUnsafe()`.
+let random = bytes =>
+  new Promise((resolve, reject) => {
+    // `Buffer.allocUnsafe()` is faster because it doesn’t flush the memory.
+    // Memory flushing is unnecessary since the buffer allocation itself resets
+    // the memory with the new bytes.
+    crypto.randomFill(Buffer.allocUnsafe(bytes), (err, buf) => {
+      if (err) {
+        reject(err)
+      } else {
+        resolve(buf)
+      }
+    })
+  })
+
+let customAlphabet = (alphabet, defaultSize = 21) => {
+  // First, a bitmask is necessary to generate the ID. The bitmask makes bytes
+  // values closer to the alphabet size. The bitmask calculates the closest
+  // `2^31 - 1` number, which exceeds the alphabet size.
+  // For example, the bitmask for the alphabet size 30 is 31 (00011111).
+  let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1
+  // Though, the bitmask solution is not perfect since the bytes exceeding
+  // the alphabet size are refused. Therefore, to reliably generate the ID,
+  // the random bytes redundancy has to be satisfied.
+
+  // Note: every hardware random generator call is performance expensive,
+  // because the system call for entropy collection takes a lot of time.
+  // So, to avoid additional system calls, extra bytes are requested in advance.
+
+  // Next, a step determines how many random bytes to generate.
+  // The number of random bytes gets decided upon the ID size, mask,
+  // alphabet size, and magic number 1.6 (using 1.6 peaks at performance
+  // according to benchmarks).
+  let step = Math.ceil((1.6 * mask * defaultSize) / alphabet.length)
+
+  let tick = (id, size = defaultSize) =>
+    random(step).then(bytes => {
+      // A compact alternative for `for (var i = 0; i < step; i++)`.
+      let i = step
+      while (i--) {
+        // Adding `|| ''` refuses a random byte that exceeds the alphabet size.
+        id += alphabet[bytes[i] & mask] || ''
+        if (id.length >= size) return id
+      }
+      return tick(id, size)
+    })
+
+  return size => tick('', size)
+}
+
+let nanoid = (size = 21) =>
+  random((size |= 0)).then(bytes => {
+    let id = ''
+    // A compact alternative for `for (var i = 0; i < step; i++)`.
+    while (size--) {
+      // It is incorrect to use bytes exceeding the alphabet size.
+      // The following mask reduces the random byte in the 0-255 value
+      // range to the 0-63 value range. Therefore, adding hacks, such
+      // as empty string fallback or magic numbers, is unneccessary because
+      // the bitmask trims bytes down to the alphabet size.
+      id += urlAlphabet[bytes[size] & 63]
+    }
+    return id
+  })
+
+module.exports = { nanoid, customAlphabet, random }