## Title
Bar clock always shows weekday/month names in English, ignoring system locale (LANG)

## Description

The bar clock widget (`omarchy.clock`) always renders weekday names (`dddd`/`ddd`) and month names (`MMMM`/`MMM`) in English, regardless of the system locale. Setting `LANG`/`LC_TIME` to a non-English locale (e.g. `es_MX.UTF-8`) correctly changes every other locale-aware value on the system, but the clock widget in the bar is unaffected.

This used to work correctly under the old waybar-based bar (pre-Quattro); it broke after the migration to the Quickshell-based `omarchy-shell`.

## Steps to reproduce

1. Set a non-English system locale, e.g.:
   ```
   localectl set-locale LANG=es_MX.UTF-8
   ```
   and reboot.
2. Confirm the locale is applied system-wide:
   ```
   $ localectl status
   System Locale: LANG=es_MX.UTF-8
   $ systemctl --user show-environment | grep LANG
   LANG=es_MX.UTF-8
   ```
3. Set the bar clock format to include a weekday/month token, e.g. `dddd HH:mm` (the default).
4. Observe the bar: it shows `Saturday 14:05` instead of the expected `sábado 14:05`.

## Root cause

`BarWidget.qml` for the clock plugin formats the date with the QML global function `Qt.formatDateTime(date, format)`:

https://github.com/basecamp/omarchy/blob/master/shell/plugins/panels/clock/BarWidget.qml

```qml
function formatted(date) {
  return Qt.formatDateTime(date, activeFormat.replace(/ww/g, Model.isoWeekLiteral(date.getFullYear(), date.getMonth(), date.getDate())))
}
```

The two-argument `Qt.formatDateTime(date, format)` overload does **not** use the application's default locale for textual tokens (`dddd`, `ddd`, `MMMM`, `MMM`) — it always formats those using English/C-locale names, independent of `Qt.locale()` or the process environment.

I confirmed this directly against the running `quickshell` binary (`Quickshell 0.3.0`) with `LANG=es_MX.UTF-8 LC_ALL=es_MX.UTF-8`:

```
Qt.locale().name:                         es_MX
Qt.formatDateTime(d, "dddd d MMMM"):      Saturday 15 August      ← wrong
d.toLocaleString(Qt.locale(), "dddd HH:mm"): sábado 14:05         ← correct
```

So `Qt.locale()` correctly resolves to `es_MX` (the system/env locale is picked up fine), but `Qt.formatDateTime()` simply doesn't consult it for weekday/month names. `Date.prototype.toLocaleString(locale, format)` (and `toLocaleDateString`/`toLocaleTimeString`), by contrast, do honor the passed-in `QLocale` and render the correct localized names, while still supporting the same format-token syntax (including the custom `ww` week-number substitution already done by `Model.isoWeekLiteral`).

## Suggested fix

Swap the formatting call in `formatted()` to a locale-aware one:

```qml
function formatted(date) {
  return date.toLocaleString(Qt.locale(), activeFormat.replace(/ww/g, Model.isoWeekLiteral(date.getFullYear(), date.getMonth(), date.getDate())))
}
```

I applied exactly this one-line change locally and confirmed the bar clock now renders correctly in Spanish (`sáb 15 ago 01:47` instead of `Sat 15 Aug 01:47`) after an `omarchy-restart-shell`. No other format tokens (vertical format, `'W'ww` week literal, AM/PM) regressed in my testing.

I didn't find any other use of `Qt.formatDateTime` elsewhere in `shell/`, so this appears to be the only spot affected.

## Environment

- Omarchy: 4.0.0-1
- quickshell-git: 0.3.0.r20.g28771c7-1
- Hyprland: 0.56.2-1
- Locale: `LANG=es_MX.UTF-8`