Route account lookups through the blind index and keep it fresh on write

These are the paths that must stop depending on deterministic encryption
before storage can move to AES-GCM. Each keeps its original ciphertext
comparison in the same statement, so behaviour is unchanged today and no
account becomes unreachable during the transition.

Lookups:
- auth/login.php — passenger sign-in matched the raw value against the
  encrypted column, which only works because encryptData() is CBC with a
  fixed IV.
- auth/passenger/register.php and auth/driver/register.php — duplicate
  detection. Without the index these would stop detecting existing accounts
  under GCM and allow the same phone to register twice.

Writes now populate the index in the same statement as the value:
- both registration paths write phone/email/name indexes with the row;
  driver indexes are computed before the encryption pass, since the raw
  values are unavailable afterwards.
- passenger profile update and admin driver update refresh the index when
  the underlying field changes. For the composite name index the untouched
  half is read back from the row.

Adds --audit to the backfill script: recomputes every index from its
encrypted value and reports missing or stale entries. Drift here is silent
by nature — it surfaces only when a real search fails.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/auth/passenger/register.php

@@ -103,8 +103,17 @@ try {
     // Step 6: التحقق من وجود المستخدم (Database Check)
     // ======================================================
     $step = 6;
-    $checkStmt = $con->prepare("SELECT id FROM passengers WHERE phone = ?");
-    $checkStmt->execute([$phoneNumber_encrypted]);
+    // كشف التكرار عبر الفهرس الأعمى + المقارنة القديمة: بدون الفهرس يفشل
+    // الكشف بعد الانتقال إلى GCM فيُسمح بتسجيل نفس الرقم مرتين.
+    global $blindIndex;
+    $phoneBidx = $blindIndex ? $blindIndex->index('passengers.phone', $phoneNumber) : null;
+    $emailBidx = $blindIndex ? $blindIndex->index('passengers.email', $email) : null;
+    $nameBidx  = $blindIndex ? $blindIndex->index('passengers.name', trim("$firstName $lastName")) : null;
+
+    $checkStmt = $con->prepare(
+        "SELECT id FROM passengers WHERE phone = ? OR (? IS NOT NULL AND phone_bidx = ?)"
+    );
+    $checkStmt->execute([$phoneNumber_encrypted, $phoneBidx, $phoneBidx]);
     
     if ($checkStmt->rowCount() > 0) {
         error_log("$logTag Step 6 Error: User already exists.");
@@ -119,8 +128,8 @@ try {
     error_log("$logTag Step 7: Inserting into passengers table...");
 
     $insertStmt = $con->prepare("
-        INSERT INTO passengers (id, first_name, last_name, email, phone, password, gender, birthdate, site, sosPhone, education, employmentType, maritalStatus, status, created_at, updated_at)
-        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'active', NOW(), NOW())
+        INSERT INTO passengers (id, first_name, last_name, email, phone, password, gender, birthdate, site, sosPhone, education, employmentType, maritalStatus, status, created_at, updated_at, phone_bidx, email_bidx, name_bidx)
+        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 'active', NOW(), NOW(), ?, ?, ?)
     ");
     $success = $insertStmt->execute([
         $uniqueId, 
@@ -135,7 +144,11 @@ try {
         $unknown_encrypted, 
         $unknown_encrypted, 
         $unknown_encrypted, 
-        $unknown_encrypted 
+        $unknown_encrypted,
+        // فهارس البحث: تُكتب مع السجل حتى يكون قابلاً للبحث فوراً
+        $phoneBidx,
+        $emailBidx,
+        $nameBidx
     ]);
 
     if (!$success) {