Plugins running in iframe sandboxes previously lacked access to the user's regional formatting settings (dateLocale, timeFormat 12h/24h, timeZone, and firstDayOfWeek) unless they requested privileged settings:read permissions.
This mirrors the host's resolved presentation preferences into the plugin sandbox:
- Adds RegionalSnapshot (locale, dateLocale, hour12, timeZone, firstDayOfWeek) to BackgroundInit, SlotInit, and LocaleChangeMsg.
- Implements snapshotRegionalSettings() in host-bridge, reusing host resolveDateLocale() and getEffectiveTimeZone().
- Subscribes stores/plugin-store.ts to useSettingsStore to broadcast updates to running sandboxes when regional preferences change.
- Exposes api.i18n.formatTime(date, options) and api.i18n.formatDate(date, options) along with regional getters on api.i18n.