feat: add calendar visibility picker

Derive session calendars from event metadata and apply one visibility contract to month rendering, appointment focus, and search without filtering persistence writes.

Add keyboard picker coverage, full-model save regression tests, documentation, warning-clean builds, sanitizer verification, and live PTY terminal restoration checks.

README.md

@@ -15,7 +15,9 @@ Use arrow keys or `h j k l` to move, `PageUp`/`PageDown` or `p`/`n` to change
 month, and `t` for today. On a day with appointments, `Tab` and `Shift-Tab`
 move focus through them and `Enter` opens the appointment reader. In the
 reader, arrows/Vim keys or Tab variants browse the day's appointments and
-`Esc` returns to the month. Press `a` to add an appointment. Focus an
+`Esc` returns to the month. Press `c` to open the calendar picker; arrows or
+`j`/`k` select a calendar and `Enter` toggles its in-session visibility. Press
+`a` to add an appointment. Focus an
 appointment and press `e` to edit it or `d` to delete it. Forms use `Tab` and
 `Shift-Tab` (or arrows) between fields, `Space` for the all-day toggle,
 `Ctrl-S` to save, and `Esc` to cancel. Back in the calendar, `u` undoes the
@@ -46,7 +48,9 @@ clearly operate on the entire series.
 Search expands recurring matches within five years on either side of the
 currently selected date. This finite window keeps unbounded recurrence rules
 responsive while one-time and recurring results share the same chronological
-result list.
+result list. Hidden calendars are excluded consistently from the month grid,
+appointment focus, and search. Visibility is session-only presentation state;
+saves always retain events from hidden calendars.
 
 Calendars containing features this version cannot preserve—such as `RDATE`,
 detached recurrence overrides, ordinal `BYDAY`, embedded `VTIMEZONE`