Implement bulk export of client answers for coaches and enhance database handling in db_init.php

tests/Integration/AppQuestionnairesBulkTest.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Integration;
+
+use Tests\Support\DatabaseSeeder;
+use Tests\Support\QdbTestCase;
+
+final class AppQuestionnairesBulkTest extends QdbTestCase
+{
+    public function testCoachLoadsBulkAnswers(): void
+    {
+        $this->submitFixtureQuestionnaire();
+        $login = $this->api()->loginMobileAndGetToken(
+            DatabaseSeeder::COACH_USERNAME,
+            DatabaseSeeder::PASSWORD
+        );
+        $res = $this->api()->withMobileToken($login['token'], 'GET', 'app_questionnaires', null, [
+            'answersBulk' => '1',
+        ]);
+        $this->assertApiOk($res);
+        $this->assertTrue($res['data']['encrypted'] ?? false);
+        $plain = qdb_decrypt_sensitive_envelope($res['data'], $login['token']);
+        $payload = json_decode($plain, true, 512, JSON_THROW_ON_ERROR);
+        $this->assertIsArray($payload['clients'] ?? null);
+        $found = null;
+        foreach ($payload['clients'] as $row) {
+            if (($row['clientCode'] ?? '') === $this->fixture()->clientCode) {
+                $found = $row;
+                break;
+            }
+        }
+        $this->assertNotNull($found, 'fixture client missing from bulk payload');
+        $this->assertNotEmpty($found['questionnaires'] ?? []);
+        $qn = $found['questionnaires'][0];
+        $this->assertSame($this->fixture()->questionnaireId, $qn['questionnaireID'] ?? null);
+        $this->assertNotEmpty($qn['answers'] ?? []);
+    }
+
+    public function testReadDbOpenUsesCacheOnSecondCall(): void
+    {
+        [$pdo1, $tmp1] = qdb_open(false);
+        [$pdo2, $tmp2] = qdb_open(false);
+        $this->assertSame(QDB_READONLY_CACHE_HANDLE, $tmp1);
+        $this->assertSame(QDB_READONLY_CACHE_HANDLE, $tmp2);
+        $this->assertSame($pdo1, $pdo2);
+        qdb_discard($tmp1, null);
+        qdb_discard($tmp2, null);
+    }
+}