Migrate remaining encrypted-column lookups to the blind index

Completes the set of queries that matched a freshly encrypted value against a
stored one, which only works while encryption is deterministic. Each keeps its
original comparison and adds an index comparison in the same WHERE, so nothing
changes today.

- passenger sign-in by email, service-staff sign-in, Firebase token lookup
- driver lookup by phone and by national number
- admin ride lookup and ride monitor (both tables)
- nabeh: driver status, user resolution, ride history, complaint submission

transit_org_admins lives in the transit database and has no index column, so
login there falls back to decrypting the small set of active admins and
comparing normalised numbers.

Schema: adds users.email_bidx/phone_bidx and driver.national_bidx with their
indexes.

Verified that every :*_bidx placeholder introduced is actually bound — an
unbound one is a fatal error at request time, not a silent miss.

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

backend/nabeh/resolve_user.php

@@ -59,12 +59,15 @@ try {
     global $encryptionHelper;
 
     $encryptedPhone = $encryptionHelper->encryptData($phone);
+    global $blindIndex;
+    $dBidx = $blindIndex ? $blindIndex->index('driver.phone', $phone) : null;
+    $pBidx = $blindIndex ? $blindIndex->index('passengers.phone', $phone) : null;
 
     // Look for driver first
     $stmt = $db->prepare(
-        "SELECT id, phone, first_name, last_name FROM driver WHERE phone = :phone LIMIT 1"
+        "SELECT id, phone, first_name, last_name FROM driver WHERE phone = :phone OR (:bidx IS NOT NULL AND phone_bidx = :bidx) LIMIT 1"
     );
-    $stmt->execute([':phone' => $encryptedPhone]);
+    $stmt->execute([':phone' => $encryptedPhone, ':bidx' => $dBidx]);
     $driver = $stmt->fetch(PDO::FETCH_ASSOC);
 
     if ($driver) {
@@ -86,9 +89,9 @@ try {
 
     // Fallback: look for passenger
     $stmt = $db->prepare(
-        "SELECT id, phone, first_name, last_name FROM passengers WHERE phone = :phone LIMIT 1"
+        "SELECT id, phone, first_name, last_name FROM passengers WHERE phone = :phone OR (:bidx IS NOT NULL AND phone_bidx = :bidx) LIMIT 1"
     );
-    $stmt->execute([':phone' => $encryptedPhone]);
+    $stmt->execute([':phone' => $encryptedPhone, ':bidx' => $pBidx]);
     $passenger = $stmt->fetch(PDO::FETCH_ASSOC);
 
     if ($passenger) {