Add full frontend UI for five backend features: bank reconciliation (3-step
stepper workflow), payee management (CRUD with alias chips), transaction splits
(expandable rows + split editor), plugins (card grid), and real-time SignalR
notifications (bell dropdown with badge). Fix backend PayeeResponse to expose
alias IDs for deletion.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>