Deduplicate notifications on WearOS when using HA app on watch and phone

**Home Assistant Android app version(s):**
- phone: 2026.2.1-full
- watch: 2026.2.1

**Android version(s):**
- phone: Android 16
- watch: WearOS 6.1

**Device model(s):**
- phone: Pixel 9 Pro
- watch: Pixel Watch 3

**Home Assistant version:**
- Core 2026.1.3

**Last working Home Assistant release (if known):**
- Did not work since at least 2026.12

**Description of problem, include YAML if issue is related to notifications:**
Non-targeted notifications are received by both the phone and the watch, but appear twice on the watch.

The phone seems to mirror its HA notifications to the watch, which has already received its own notification using its own HA app.

The issue is that when notification mirroring is disabled for the HA app, the watch receives not two, not one, but *no notifications at all* anymore.

**Additional information:**
This seems to be a common issue. There seems to be a fix that needs to be implemented in the phone app, see .