Adds a "Zahlungen importieren" button to the member Zahlungen tab that opens
a dedicated window: point it at a GnuCash file (plain or gzip-compressed
XML, defaults to the file configured in Optionen), pick one of its accounts,
and narrow the account's bookings down with a description-contains filter
and an optional date range.
Each matching booking gets a checkbox to mark it for import as a payment.
Before anything is ticked, bookings are cross-checked against this member's
existing payments by date + amount; a match is highlighted and its checkbox
is refused, so re-importing the same statement can't create a duplicate
payment. Only bookings with a positive amount on the selected account are
offered, since those are the ones that make sense as an incoming payment.
Parsing lives in ccma.services.gnucash_import, independent of the UI, and
is covered by tests against a synthetic GnuCash XML fixture (plain and
gzip-compressed) -- no gnucash/piecash dependency needed since the native
file format is just XML.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
