fix(06.2): WR-01 replace fixed-suffix password generation with fully-random positional injection

frontend/src/components/admin/AdminUsersTab.vue

@@ -290,16 +290,38 @@ const newUser = reactive({
 })
 
 function generateRandomPassword() {
-  const charset = 'ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnpqrstuvwxyz23456789!@#$%^&*'
+  const upper = 'ABCDEFGHJKLMNPQRSTUVWXYZ'
+  const lower = 'abcdefghijkmnpqrstuvwxyz'
+  const digits = '23456789'
+  const special = '!@#$%^&*'
+  const charset = upper + lower + digits + special  // 64 chars — 256 % 64 === 0, no modulo bias
+
+  // Generate 16 random positions
   const arr = new Uint8Array(16)
   crypto.getRandomValues(arr)
-  let pw = ''
-  for (const byte of arr) {
-    pw += charset[byte % charset.length]
+  const chars = Array.from(arr, byte => charset[byte % charset.length])
+
+  // Inject one guaranteed character from each required class at random positions
+  // using four additional random bytes to pick the injection positions.
+  const posArr = new Uint8Array(8)
+  crypto.getRandomValues(posArr)
+  const required = [
+    upper[posArr[0] % upper.length],
+    lower[posArr[1] % lower.length],
+    digits[posArr[2] % digits.length],
+    special[posArr[3] % special.length],
+  ]
+  // Place each required char at a distinct position (0..3) in the array
+  for (let i = 0; i < 4; i++) {
+    chars[i] = required[i]
   }
-  // Ensure all character classes are represented
-  pw = pw.slice(0, 12) + 'A1!'
-  return pw
+  // Shuffle using Fisher-Yates with the last 4 random bytes as seeds
+  for (let i = chars.length - 1; i > 0; i--) {
+    const j = posArr[4 + (i % 4)] % (i + 1)
+    ;[chars[i], chars[j]] = [chars[j], chars[i]]
+  }
+
+  return chars.join('')
 }
 
 function generatePassword() {