fix: show events starting at Unix timestamp 0

[MiMoHo]

Type of change(s)

• Bug fix

What changed and why

Several EventsDao queries carried a stale AND start_ts != 0 clause inherited from the Simple Calendar era. start_ts is a Unix timestamp in seconds, so start_ts == 0 is exactly 1970-01-01 00:00:00 UTC. Any event landing on that instant — including all-day or yearly-recurring events whose start falls on epoch 0 (e.g. New Year's Day 1970 in GMT+0) — was stored in the database but silently filtered out of day/list views, search, and reboot reminder rescheduling, so it never became visible.

The clause was also inconsistent: the sibling queries without calendarIds (getOneTimeEventsOrTasksFromTo, getRepeatableEventsOrTasksWithCalendarIds(toTS)) never had it, confirming it is a legacy heuristic rather than intentional behaviour. No code inserts start_ts = 0 as a hidden sentinel (only the Event model default 0L and the UI-only ListEvent.empty).

This PR removes the clause from the five affected queries:

• getOneTimeEventsFromToWithCalendarIds
• getOneTimeEventsFromToWithTypesForSearch
• getRepeatableEventsOrTasksWithCalendarIds(toTS, calendarIds)
• getRepeatableEventsOrTasksWithTypesForSearch
• getEventsOrTasksAtReboot

Removing it from the reboot query is safe: a non-repeating event at ts 0 is already excluded by (start_ts > :currentTS OR repeat_interval != 0), while a repeating one legitimately has future occurrences that need reminders. The now-obsolete legacy comment above that query is dropped.

The existing instrumented test bug440_EventAtMidnightOnFirstJan1970 (previously wrapped in expectedFailure) is unwrapped so it now passes, and the detekt baseline is updated to match the shortened query lines.

Tests performed

Built the fossDebug variant and verified on an Android 15 (API 35) emulator:

Set device timezone to UTC (Etc/GMT); created event at Jan 1 1970 12:00 AM (start_ts=0). Reminder notification fired showing 'January 1 1970, 12:00 AM'. Searching 'Epoch' returned the event under JANUARY 1970 / 1 Thursday / Epoch 12:00 AM. Previously start_ts!=0 filter would hide it.

Also confirmed detekt, lint, unit tests and the build all pass locally (CI-equivalent).

Closes the following issue(s)

• Closes Events starting on the timestamp 0 aren't visible in the app #440

Checklist

• I read the contribution guidelines.
• I manually tested my changes on device/emulator.
• I updated the "Unreleased" section in CHANGELOG.md (if applicable).
• I have self-reviewed my pull request (no typos, formatting errors, etc.).
• I understand every change in this pull request.

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