Add blind-index search layer; fix captain detail 200-with-empty-body

Searching encrypted columns currently works only because encryptData() is
AES-CBC with a fixed IV, i.e. deterministic. That determinism is what leaks
equality and shared prefixes, and it is why moving storage to AES-GCM would
break every lookup. This separates the two concerns.

- core/Security/BlindIndex.php: HMAC-SHA256 over a normalised value, keyed by
  a secret pepper. Phone numbers have a small keyspace, so a bare SHA-256
  would be reversible by enumeration; the pepper lives in the environment, not
  the database. The scope string includes table and field so the same number
  does not produce a matching index across tables.
  Normalisation unifies local/international phone forms, lowercases emails and
  folds Arabic alef/ya/ta-marbuta and diacritics for names.
- migrations/: nullable *_bidx columns plus indexes, and the missing
  adminUser.status/approved_by/approved_at columns that admin approvals need.
- scripts/backfill_blind_index.php: restartable, batched, --dry-run capable,
  touches only index columns.
- Admin lookups by phone/email now match the index, keeping the old ciphertext
  comparison in the same query so search keeps working until the backfill runs.
  bootstrap exposes $blindIndex as null when no pepper is configured.

Also: AdminCaptain/getCaptainDetailsById.php selected driver.education, a
column absent from this schema. The PDOException was uncaught, so the client
received an empty body with HTTP 200 — the "non-JSON response" seen when
opening a captain. It now omits the column, catches the error, reports it as
JSON, and requires an admin role.

Console: opening any sidebar section refetches its data instead of showing
what was loaded when the console started.

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

backend/Admin/AdminCaptain/getCaptainDetailsById.php

@@ -1,9 +1,18 @@
 <?php
 require_once __DIR__ . '/../../connect.php';
 
-// تشفير driver_id قبل استخدامه في SQL
+if ($role !== 'admin' && $role !== 'super_admin') {
+    http_response_code(403);
+    echo json_encode(['error' => 'Unauthorized: Admin access required']);
+    exit;
+}
+
 $driver_id = filterRequest("driver_id");
 
+if (empty($driver_id)) {
+    jsonError("driver_id is required", 400);
+}
+
 $sql = "SELECT
     `driver`.`id`,
     `driver`.`phone`,
@@ -14,7 +23,6 @@ $sql = "SELECT
     `driver`.`site`,
     `driver`.`first_name`,
     `driver`.`last_name`,
-    `driver`.`education`,
     `driver`.`employmentType`,
     `driver`.`maritalStatus`,
     `driver`.`created_at`,
@@ -59,14 +67,23 @@ WHERE `driver`.`id` = :driver_id
 ORDER BY passengerAverageRating DESC
 LIMIT 10";
 
-$stmt = $con->prepare($sql);
-$stmt->bindParam(':driver_id', $driver_id);
-$stmt->execute();
-
-$result = $stmt->fetchAll(PDO::FETCH_ASSOC);
+try {
+    $stmt = $con->prepare($sql);
+    $stmt->bindParam(':driver_id', $driver_id);
+    $stmt->execute();
+    $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
+} catch (PDOException $e) {
+    // بلا هذا الالتقاط كان الاستثناء يُنهي السكربت فيصل للعميل جسم فارغ
+    // بحالة HTTP 200، فيظهر كـ "رد غير JSON".
+    error_log("[getCaptainDetailsById] " . $e->getMessage());
+    jsonError("Could not read the captain record: " . $e->getMessage(), 500);
+}
 
 // فك تشفير الحقول الحساسة بعد الجلب
 foreach ($result as &$row) {
+    foreach (['phone','email','gender','birthdate','site','first_name','last_name','employmentType','maritalStatus'] as $f) {
+        if (!array_key_exists($f, $row)) $row[$f] = null;
+    }
     $row['phone'] = $encryptionHelper->decryptData($row['phone']);
     $row['email'] = $encryptionHelper->decryptData($row['email']);
     $row['gender'] = $encryptionHelper->decryptData($row['gender']);
@@ -74,7 +91,6 @@ foreach ($result as &$row) {
     $row['site'] = $encryptionHelper->decryptData($row['site']);
     $row['first_name'] = $encryptionHelper->decryptData($row['first_name']);
     $row['last_name'] = $encryptionHelper->decryptData($row['last_name']);
-    $row['education'] = $encryptionHelper->decryptData($row['education']);
     $row['employmentType'] = $encryptionHelper->decryptData($row['employmentType']);
     $row['maritalStatus'] = $encryptionHelper->decryptData($row['maritalStatus']);
 }