edit --due with date-only sets hour:0 minute:0 instead of date-only reminder

[yulin0629]

Description

When using remindctl edit <id> --due "2026-02-04" (date-only, no time component), the resulting reminder still has a time of 12:00 AM instead of being a true date-only (all-day) reminder.

Root Cause

In Sources/RemindCore/EventKitStore.swift, the calendarComponents(from:) method always includes .hour and .minute:

private func calendarComponents(from date: Date) -> DateComponents {
    calendar.dateComponents([.year, .month, .day, .hour, .minute], from: date)
}

When the input is a date-only string like "2026-02-04", the parsed Date defaults to midnight (00:00), so hour: 0, minute: 0 are always written into dueDateComponents. Apple Reminders treats this as a timed reminder at 12:00 AM, rather than a date-only reminder.

Expected Behavior

A date-only input (e.g., --due "2026-02-04") should produce a true all-day reminder — the same as toggling off the time switch in the Reminders GUI. This means dueDateComponents should only contain [.year, .month, .day] without .hour and .minute.

Suggested Fix

Track whether the user provided a time in the input. If not, use date-only components:

private func calendarComponents(from date: Date, dateOnly: Bool) -> DateComponents {
    if dateOnly {
        return calendar.dateComponents([.year, .month, .day], from: date)
    }
    return calendar.dateComponents([.year, .month, .day, .hour, .minute], from: date)
}

The dateOnly flag can be derived from the DateParsing layer — formats like YYYY-MM-DD, today, and tomorrow are date-only, while YYYY-MM-DD HH:mm and ISO 8601 with time are not.

Environment

• remindctl 0.1.1
• macOS 15 (Sequoia)