Extend churn probe with UDF registration

PDO churn alone (raw open/close 0..500 times) didn't reproduce
either failing-test bug. Each driver setUp also registers ~44 UDFs
via sqliteCreateFunction. Add UDF registration to each churn
iteration to mirror the driver, in case stale FUNC_SLOTS state
across sqlite3_create_function_v2 calls is the trigger.

Author: JanJakes

.github/workflows/phpunit-tests-turso.yml

@@ -1023,13 +1023,33 @@ jobs:
           // If the bug reproduces past some N, we have a minimal repro
           // and can bisect what specifically accumulates.
           function setup_and_run(int $churn_count): array {
+              // Mimic the driver's setUp: register a bunch of UDFs and run
+              // common PRAGMAs, like WP_PDO_MySQL_On_SQLite::__construct does.
+              $udf_names = [
+                  'throw','month','monthnum','year','day','hour','minute','second','week',
+                  'weekday','dayofweek','dayofmonth','unix_timestamp','now','md5','curdate',
+                  'rand','from_unixtime','localtime','localtimestamp','isnull','if','regexp',
+                  'field','log','least','greatest','get_lock','release_lock','ucase','lcase',
+                  'concat','date_add','date_sub','dayname','monthname','quarter','last_day',
+                  'time_to_sec','timestampdiff','date_format','find_in_set','char_length','format',
+              ];
               for ($i = 0; $i < $churn_count; $i++) {
-                  $p = new PDO('sqlite::memory:');
+                  $pdo_class = PHP_VERSION_ID >= 80400 ? PDO\SQLite::class : PDO::class;
+                  $p = new $pdo_class('sqlite::memory:');
                   $p->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+                  $p->setAttribute(PDO::ATTR_TIMEOUT, 30);
+                  $p->setAttribute(PDO::ATTR_STRINGIFY_FETCHES, true);
+                  $p->query('PRAGMA foreign_keys = ON');
+                  foreach ($udf_names as $name) {
+                      if ($p instanceof PDO\SQLite) {
+                          $p->createFunction($name, function (...$a) { return ''; });
+                      } else {
+                          $p->sqliteCreateFunction($name, function (...$a) { return ''; });
+                      }
+                  }
                   $p->exec('CREATE TABLE t (id INT, v TEXT)');
                   $p->exec("INSERT INTO t VALUES (1, 'a'), (2, 'b'), (3, 'c')");
                   $p->query('SELECT * FROM t');
-                  // CREATE TEMP TABLE on each — exercises temp pager
                   $p->exec('CREATE TEMPORARY TABLE t2 (id INT)');
                   $p->exec("INSERT INTO t2 VALUES (1)");
                   unset($p);