Add unified tickets table with ticket_type discriminator column ('archer'|'jira').
Migration preserves Jira ticket IDs for FK integrity, updates junction table FK,
and renames old tables to *_legacy for rollback path.
New /api/tickets router provides full CRUD with type-aware validation, plus all
Jira integration endpoints (lookup, sync, create-in-jira). Old routes
(/api/jira-tickets, /api/archer-tickets) refactored as backward-compatible
proxies querying the unified table.
Updated ivantiTodoQueue ticket-links JOIN and server.js CVE cascade queries
to reference the new tickets table.
5ef535426d
