Track iOS custom notification icon support for local alerts

[CCOSTAN]

Source

• Split from Joanna Idea Scout - 2026-05-29 #1772 item 1.
• Upstream reference: Add custom notification icons for automations home-assistant/iOS#4672
• Related digest context: Joanna Idea Scout - 2026-05-28 #1771 item 1 also surfaced this same iOS notification icon idea.

Idea

Home Assistant iOS is adding support for custom notification icons in push payloads through fields such as notification_icon and icon_url. Once the iOS app and push relay support are fully available, local alerts could show task-specific icons instead of the default Home Assistant app icon.

Local direction

• Confirm the iOS app release and payload support before changing Home Assistant YAML.
• Update the shared notification script/package path to accept optional icon fields without changing existing notification behavior.
• Start with high-signal alerts where icons add context, such as backup status, appliance completion, cameras, and health/coaching reminders.
• Keep the implementation optional so existing Android/iOS notification flows continue to work unchanged.

Acceptance notes

• Notification icon fields are documented in the local package/script comments or README if behavior changes.
• A small set of high-value alerts includes meaningful icons.
• Home Assistant config validation passes after any YAML changes.