Fix DROP INDEX IF EXISTS syntax for older MySQL versions

Replace unsupported DROP INDEX IF EXISTS with information_schema check.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

database/migrations/Phase_64_002_fix_daily_cash_movements_schema.php

@@ -23,8 +23,14 @@ return function (\App\Core\Database $db): void {
         }
     }
 
-    $db->raw("ALTER TABLE `{$table}` DROP INDEX IF EXISTS `uk_date_bank`");
-    $db->raw("ALTER TABLE `{$table}` DROP INDEX IF EXISTS `uk_date_safe`");
+    $idxBank = $db->selectOne("SELECT 1 FROM information_schema.statistics WHERE table_schema = DATABASE() AND table_name = ? AND index_name = 'uk_date_bank'", [$table]);
+    if ($idxBank) {
+        $db->raw("ALTER TABLE `{$table}` DROP INDEX `uk_date_bank`");
+    }
+    $idxSafe = $db->selectOne("SELECT 1 FROM information_schema.statistics WHERE table_schema = DATABASE() AND table_name = ? AND index_name = 'uk_date_safe'", [$table]);
+    if ($idxSafe) {
+        $db->raw("ALTER TABLE `{$table}` DROP INDEX `uk_date_safe`");
+    }
 
     $idx = $db->selectOne("SELECT 1 FROM information_schema.statistics WHERE table_schema = DATABASE() AND table_name = ? AND index_name = 'idx_movement_date'", [$table]);
     if (!$idx) {