Harden recurring cron, bulk delete, error handling; fix semgrep CI

Continued fixes from the multi-agent review:

- recurring tickets cron: now that the parse error is fixed the job runs,
  exposing two latent bugs. (1) next_run_at was only advanced after the
  full success path, so any failure (e.g. a NULL created_by passed to the
  non-nullable assignTicket() $assignedBy -> TypeError) left it in the past
  and re-created a duplicate ticket every cron cycle. Added an atomic
  claimForRun() (conditional UPDATE gated on still-due) called BEFORE
  creation, which also prevents overlapping runs from double-creating.
  (2) The cron used a raw mysqli with no utf8mb4, corrupting non-ASCII
  content; it now uses Database::getConnection(). Also guard the assignment
  so created_by NULL falls back to the assignee.
- bulk delete: attachment files were unlinked inside the DB transaction, so
  an atomic-mode rollback restored rows but the files were already gone.
  deleteTicket() can now defer file removal to the caller, and
  BulkOperationsModel deletes files only after a successful commit.
- UserModel: back-tick the `groups` column (reserved word on MySQL 8.0.2+).
- create_ticket_api.php: stop leaking raw DB/exception messages to callers;
  log server-side and return a generic error. (Also includes a pre-existing
  working-tree tweak that adds title to the manual-ticket dedupe hash.)
- CI: semgrep install failed under PEP 668; add --break-system-packages.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cron/create_recurring_tickets.php

@@ -16,6 +16,7 @@ chdir(dirname(__DIR__));
 
 // Include required files
 require_once 'config/config.php';
+require_once 'helpers/Database.php';
 require_once 'models/RecurringTicketModel.php';
 require_once 'models/TicketModel.php';
 require_once 'models/AuditLogModel.php';
@@ -29,17 +30,9 @@ function logMessage($message)
 logMessage("Starting recurring tickets cron job");
 
 try {
-    // Create database connection
-    $conn = new mysqli(
-        $GLOBALS['config']['DB_HOST'],
-        $GLOBALS['config']['DB_USER'],
-        $GLOBALS['config']['DB_PASS'],
-        $GLOBALS['config']['DB_NAME']
-    );
-
-    if ($conn->connect_error) {
-        throw new Exception("Database connection failed: " . $conn->connect_error);
-    }
+    // Create database connection (Database::getConnection sets utf8mb4 so
+    // non-ASCII titles/descriptions aren't corrupted on insert).
+    $conn = Database::getConnection();
 
     // Initialize models
     $recurringModel = new RecurringTicketModel($conn);
@@ -57,6 +50,14 @@ try {
         logMessage("Processing recurring ticket ID: " . $recurring['recurring_id']);
 
         try {
+            // Claim the schedule FIRST (atomic advance of next_run_at). If another
+            // cron run already claimed it, or it's no longer due, skip it — this
+            // prevents duplicate-ticket floods if a later step throws.
+            if (!$recurringModel->claimForRun($recurring['recurring_id'])) {
+                logMessage("Skipped (already claimed or not due): " . $recurring['recurring_id']);
+                continue;
+            }
+
             // Prepare ticket data
             $ticketData = [
                 'title' => processTemplate($recurring['title_template']),
@@ -74,9 +75,12 @@ try {
                 $ticketId = $result['ticket_id'];
                 logMessage("Created ticket: " . $ticketId);
 
-                // Assign to user if specified
-                if ($recurring['assigned_to']) {
-                    $ticketModel->assignTicket($ticketId, $recurring['assigned_to'], $recurring['created_by']);
+                // Assign to user if specified. assignTicket() requires a non-null
+                // "assigned_by"; fall back to the assignee when created_by is null
+                // (recurring schedules may have no creator).
+                if (!empty($recurring['assigned_to'])) {
+                    $assignedBy = (int)($recurring['created_by'] ?? $recurring['assigned_to']);
+                    $ticketModel->assignTicket($ticketId, (int)$recurring['assigned_to'], $assignedBy);
                 }
 
                 // Log to audit
@@ -88,9 +92,6 @@ try {
                     ['source' => 'recurring', 'recurring_id' => $recurring['recurring_id']]
                 );
 
-                // Update the recurring ticket's next run time
-                $recurringModel->updateAfterRun($recurring['recurring_id']);
-
                 $created++;
             } else {
                 logMessage("ERROR: Failed to create ticket - " . ($result['error'] ?? 'Unknown error'));
@@ -104,7 +105,7 @@ try {
 
     logMessage("Completed: Created $created tickets, $errors errors");
 
-    $conn->close();
+    Database::close();
 } catch (Exception $e) {
     logMessage("FATAL ERROR: " . $e->getMessage());
     exit(1);