chore: clear pre-commit eslint warnings (unused symbols, stale disables, test any)

Cleans up the lint warnings the pre-commit hook surfaces, without any
behavioral change:

- Remove unused imports/vars/destructured props (parseISO, useEffect,
  format, durMin, roles, daysInYear, ALLOWED_PLUGIN_FILES, continuesBefore,
  isPushConnected, isSelected) and the now-unused parseDuration import.
- Drop three stale `// eslint-disable-next-line no-undef` directives that
  no longer suppress anything (browser-navigation, smime/crypto-engine).
- recurrence-expansion.test.ts: replace 39 `as any` casts with a cast-only
  `rule()` helper for partial recurrence-rule fixtures, typed access to
  utcStart/utcEnd (now on CalendarEvent), and the source's
  `Partial<CalendarEvent> & { excluded?: boolean }` for the excluded
  override. No defaults are injected, so the expansion logic sees the same
  partial rules as before (35 tests still green).

Remaining: 7 react-hooks/exhaustive-deps warnings are left as-is — adding
the missing deps changes effect/memo timing and needs per-hook review, not
a mechanical fix. tsc --noEmit clean; eslint 0 errors / 7 warnings.

components/calendar/calendar-agenda-view.tsx

@@ -5,7 +5,7 @@ import { useTranslations, useFormatter } from "next-intl";
 import { format, isToday, isTomorrow, startOfDay } from "date-fns";
 import { MapPin, Users } from "lucide-react";
 import { cn } from "@/lib/utils";
-import { parseDuration, getEventColor } from "./event-card";
+import { getEventColor } from "./event-card";
 import { getEventDayBounds, getEventEndDate, getEventStartDate, getPrimaryCalendarId } from "@/lib/calendar-utils";
 import { getParticipantCount } from "@/lib/calendar-participants";
 import type { CalendarEvent, Calendar } from "@/lib/jmap/types";
@@ -147,7 +147,6 @@ export function CalendarAgendaView({
               const calendar = calId ? calendarMap.get(calId) : undefined;
               const color = getEventColor(ev, calendar);
               const start = getEventStartDate(ev);
-              const durMin = parseDuration(ev.duration);
               const end = getEventEndDate(ev);
               const locationName = ev.locations
                 ? Object.values(ev.locations)[0]?.name