New test_postings.py walks service and route layers: add sums into
applied, negatives are allowed, update and delete round-trip, entry
deletion cascades postings, order is desc by date, update_month_entry
rejects the removed applied kwarg. Route tests assert HTTP behaviour,
invalid-date rejection, closed-month lock, tone flip after a posting,
and the "N txns" count badge renders.
Existing tests that previously set applied via update_month_entry or
the entries route now use add_posting or POST to /postings. Format
assertions updated to match the new thousands-separator number
rendering and the replaced entry-notes-row markup.
Refs #19
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
