Tasks with due dates now appear directly on the weekly calendar view,
similar to Google Calendar. Removes the tab bar UI in favor of a
unified calendar view where todos are visually distinct (secondary
color, checkbox prefix) and clickable to toggle completion.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add full VTODO/task management via Evolution Data Server Python scripts
(list, create, complete/uncomplete, delete) and integrate into the panel
with a Calendar/Tasks tab bar, task list view with priority indicators,
due date display, and a create task dialog.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CalendarService.loadEvents() replaces all cached events with only the
requested date window. The previous approach called loadEvents() on
every week navigation, causing a race with CalendarService's internal
5-minute auto-refresh (which uses narrow defaults of 31/14 days).

Key changes:
- Request wide range (180 days back, 60 days ahead) on initial load
- Navigate weeks via refreshView() which re-filters locally
- Detect when auto-refresh narrows events and re-request wide range
- Process cached events immediately on startup (before EDS is ready)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>