Jump to today, and open a period on the dates it actually has

The month can now be reached in one click instead of paging back through
the year. The button sits left of the month dropdown and sizes to its
label, so Idag and Today both fit.

Opening a period showed the wish's first year rather than the occurrence
that was clicked: a 2028 week of a yearly wish opened on 2026, and a
flexible period opened on its bounding range instead of where the planner
put it. The popover now prefills from the clicked band's own dates.
Saving a yearly wish keeps its anchor year, since the edited dates
describe the recurring pattern and not one occurrence — moving a single
year is a separate choice that does not exist yet.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ei7gCZzdd751uZtPzb1Pep

frontend/src/i18n/sv/calendar.ts

@@ -21,6 +21,7 @@ export const calendar = {
   'calendar.partner': 'Partner',
   'calendar.prevMonthAria': 'Föregående månad',
   'calendar.saveError': 'Det gick inte att spara de planerade dagarna',
+  'calendar.today': 'Idag',
   'calendar.weekdayFri': 'Fre',
   'calendar.weekdayMon': 'Mån',
   'calendar.weekdaySat': 'Lör',