Adds schema migration v3 (recurrence_parent_id column + budget_recurrence_skipped
table). On every GET /api/v1/budget, the server checks all recurring originals
(is_recurring=1, no parent) and creates missing instances for the requested month
using the same day-of-month (clamped to the last day). Deleted instances are
recorded in budget_recurrence_skipped so they are not recreated on the next visit.
Generated instances are shown with a ↩ indicator in the transaction list.
Closes BL-05.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Each summary card (Einnahmen, Ausgaben, Saldo) now shows a trend line
comparing the current month to the previous one. The previous month's
summary is fetched in parallel via the existing /budget/summary endpoint,
so there is no extra round-trip latency. Positive deltas render in green
(▲), negative in red (▼), unchanged in neutral grey (—).
Closes BL-02.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Ulas