D1 - number of reminders (default 3, max 5):
- new NUM_REMINDERS config in plugin_base.py
- new BalSpinBox widget bound to a BalConfig
- new pure helper compute_reminder_offsets(days, count): reminders spread
uniformly across the check-alive period, always before the deadline
(offset >= 1), at most one per available day, de-duplicated, earliest
first (e.g. (30,3)->[30,16,1], (2,3)->[2,1], (1,3)->[1], (0,3)->[])
- create_alarms() rewritten to use it and emit one VALARM per offset with a
DESCRIPTION reminder text
- 'Number of reminders' spin box (range 1..5) added to the settings dialog
and to the Reset list
D1b - save-only .ics (ask where, default to Desktop):
- BalCalendar.desktop_dir() helper (~/Desktop with home fallback)
- open_or_save_calendar() no longer opens the file with a calendar app; it
always shows a 'save as' dialog (.ics filter, default will_event.ics,
starting on the Desktop) and copies the file there, then confirms.
Identical behaviour on Windows/Linux/macOS. save_to_cwd -> save_ics_to.
Follow-up: removed the now-unused 'Calendar App' field from the settings
dialog (and from the Reset list). CALENDAR_APP config and
open_with_default_app left in place (unused) to avoid unrelated changes.
D2 intentionally skipped (per user request).
tests/test_group_d_alarms.py: 7 new tests (NUM_REMINDERS default/change and
all distribution rules). Full suite: 217 passed.
