fix(alerts): working notification-settings deep link + muted visibility in lists

[proofofprints]

Two pieces of polish on the v1.6 mute/notification features (found during runtime verification).

1. Dead 'Open Windows notification settings' button

The button used the shell plugin's open(), whose default URL validator only permits http(s)/mailto/tel — so the ms-settings:notifications scheme was silently rejected (clicking did nothing on Windows 11).

• Added open_notification_settings backend command that opens the OS notification settings via the OS opener (explorer ms-settings:notifications on Windows, mirroring the existing open_log_directory pattern; best-effort open/gnome-control-center on macOS/Linux).
• NotificationBanner now invokes it (with error logging) instead of the blocked shell open.

2. Muted devices weren't obvious in the lists

In the ASIC (MinerList) and OverMobile (MobileMinerList) card and table views, a muted device now:

• gets an amber tint on its card and row, and
• shows a "Muted" status badge (amber) in place of its normal status.

Muted state is read via get_muted_devices on mount and re-fetched on farm-state-updated. The selection highlight still takes precedence over the muted tint.

Note: a muted miner shows "Muted" even if online — the tint + badge make the mute obvious per the request; the detail page still shows full online/offline status. Easy to switch to showing both if preferred.

Verification

• cargo check ✅ · npx tsc --noEmit ✅
• Runtime: user to confirm the settings button now opens Windows Settings → Notifications, and muted miners show amber + "Muted" in both list views.