Add multi-item Jira ticket creation from Ivanti Queue

Select multiple queue items and create a single consolidated Jira ticket
with aggregated summary and description. Adds multi-select mode with
checkboxes, floating action bar, consolidation modal, and junction table
to track which queue items contributed to each ticket.

- Migration: jira_ticket_queue_items junction table
- POST /api/jira-tickets/:id/queue-items endpoint
- GET /api/ivanti/todo-queue/ticket-links endpoint
- ConsolidationModal component with aggregation logic
- IvantiTodoQueuePage with selection mode and ticket link badges
- Pure utility functions for summary/description generation
- 34 tests passing (backend + frontend)

backend/migrations/run-all.js

@@ -23,6 +23,7 @@ const POSTGRES_MIGRATIONS = [
     'add_compliance_item_history.js',
     'add_jira_sync_columns_pg.js',
     'add_flexible_jira_ticket_creation.js',
+    'add_multi_item_jira_ticket.js',
 ];
 
 async function runAll() {