fix(calendar-sync): drop declined events from synced output

The sync parsed PARTSTAT into a :STATUS: declined property but kept
the event. Meetings I'd declined still landed in dcal.org / gcal.org
and showed on the agenda. I added a pure --filter-declined helper
called inside --parse-ics after event collection, plus the
calendar-sync-skip-declined defvar (default t) so it can be flipped
off without code changes.

The .ics feed and the Calendar API can disagree on PARTSTAT. OOO
auto-declines sometimes only write API-side, so a few declined
events may still slip through. I'm calling this out because the
filter looks absolute from the agenda but isn't.

Tests cover Normal/Boundary/Error (11 cases). Full suite is green.

0 files changed, 0 insertions, 0 deletions