## What happened

The low-battery warning toast ("Time to recharge! Battery is down to 10%") never goes away on its own, and it comes back after every shell restart even when the laptop is plugged in again. It stays on screen indefinitely until manually clicked/dismissed.

## What I expected

The toast to disappear after its 30-second timeout (), and/or to be dismissed when AC power is reconnected.

## Steps to reproduce

1. Discharge the battery to <= 10% (threshold is 10 in the battery service).
2. The toast appears via , which sends it with urgency `critical` and `-t 30000`.
3. Observe: the toast never auto-expires. Plug in the charger — nothing dismisses it.
4. Restart the shell ( or any restart during update): the toast is restored again (and again), because critical popups are treated as never-expiring.

## Root cause analysis

In `shell/plugins/notifications/Service.qml`:

- `durationFor()` returns `0` for `NotificationUrgency.Critical`, which means the popup has no lifetime at all — the countdown timer in the popup delegate (`ticking: cardSlot.lifetime > 0 && !card.hovered`) never runs, so the toast can only be removed by user interaction.
- The `expireTimeout` the sender explicitly requested (`-t 30000` = 30000 ms) is ignored for critical notifications — `requestedDuration()` is only consulted for low/normal urgency.
- In `restorePopups()`, `popupExpired()` treats `duration 0` as "never expires and always survives restarts", so the toast is re-shown after every restart, even days later and while on AC power.

Additionally, nothing clears the low-battery warning when `UPower.onBattery` flips back to false (charging), so the notification outlives the condition it warns about.

Suggested directions (any one would resolve the user-facing issue):
- Honor a sender-provided positive `expireTimeout` even for critical urgency (perhaps with a floor, e.g. `maxPopupDuration`), so `omarchy-battery-low`'s 30s timeout applies.
- Have the battery service (`shell/plugins/services/battery/Service.qml`) dismiss/replace its warning when AC power returns (e.g. via `omarchy notification dismiss` on `onBatteryChanged`).

## Diagnostics

- Omarchy version: 4.0.4-1
- Kernel: 6.x omarchy build (`7.2.5-3-omarchy`)
- CPU: 13th Gen Intel Core i7-13620H
- GPU: Intel UHD (Raptor Lake-P) + NVIDIA RTX 5060 Max-Q (hybrid)
- Stale popup files observed in `~/.local/state/omarchy/notifications/` for days-old low-battery toasts, confirming they persist and get restored across restarts.

Workaround for affected users: `omarchy notification dismiss "Time to recharge"` clears the stuck toast.