feat(notifications): unified notification system v3.9.0

[tempus2016]

Summary

Replaces TaskMate's narrow notification surface (single global notify_service + per-badge notify_on_earn) with a unified per-event, multi-recipient configuration page in the admin panel.

Four new notification types (all opt-in, default OFF):

• 🌙 Bedtime reminder — pings the child if outstanding chores at configured time (per-child time)
• 🔥 Streak at risk — fires when an active streak (≥2 days) hasn't been extended yet
• 🎉 All chores done — celebration ping when a child finishes every chore for the day
• 📋 Actionable approvals — pending chore approval and reward claim now carry mobile-app Approve / Reject action buttons (tap-to-approve from the notification banner)

Custom scheduled notifications — parents can define their own timed reminders with name, message template ({child_name} placeholder), time, day-of-week mask, and recipient list.

Power-user taskmate_* event bus — every state change emits a clean event for Node-RED / HA automations:

• taskmate_chore_completed, taskmate_chore_approved
• taskmate_streak_updated, taskmate_perfect_week
• taskmate_reward_claimed
• taskmate_badge_earned (was already there; documented now)
• Plus per-fire taskmate_<type_id> events with recipient list

New admin tab "Notifications" with three sections:

1. Recipients — children's notify service + free-form parent list with notify service
2. Built-in matrix — full grid of (notification_type × recipient) toggles, master switch per row, inline per-child time for bedtime, inline global cutoff for streak-at-risk
3. Custom scheduled — name, message, time, day mask, recipient chips

Architecture

New coord_notifications.py (NotificationCoordinator) is the single dispatcher for every notification. Other coords (coord_chores, coord_rewards, coord_points, coord_badges) stop building messages directly and call await self.notifications.fire(type_id, context). The dispatcher handles routing, message templating (with _SafeDict so missing keys don't raise), persistent_notification, per-recipient notify.* calls, mobile actionable data, and bus event emission.

10 new WebSocket commands under taskmate/notifications/* for the panel. Full migration on first load preserves existing behaviour: pending approvals, reward claims and badge earned default ON for the seeded parent recipient (migrated from legacy notify_service setting); the four new types default OFF.

Test plan

• All 452 pytest tests pass (added 34 new tests for storage migration, dispatch, scheduler, actionable, ws, events)
• Ruff lint clean
• Manual smoke test on real HA instance:
  • Open the new Notifications admin tab — verify three sections render
  • On upgrade: legacy notify_service is migrated into a parent recipient row (no surprise behaviour)
  • Complete a chore as a child → parent gets actionable notification → tap Approve from the banner → chore approves without opening the app
  • Same for reward claims
  • Enable bedtime reminder for a child, set time near now → notification arrives only if child has outstanding chores
  • Add a custom scheduled notification → triggers at the configured time on enabled days only
  • In HA Developer Tools → Events, listen for taskmate_chore_completed → complete a chore → event payload visible

Migration / backwards compatibility

• Legacy notify_service setting is preserved (not deleted) — readable for rollback
• Pending approval / reward claim / badge earned default ON post-migration for the seeded parent — same destinations as before
• Per-badge notify_on_earn flag still honoured (extra layer above the new master toggle)
• All 4 new notification types default OFF — no surprise pings on upgrade

Fixes #N/A (no specific issue — direction set in chat session 2026-05-10)

Spec: docs/superpowers/specs/2026-05-10-notifications-overhaul-design.md (local)
Wireframe: .tmp/notifications-wireframe.html (local)
Plan: docs/superpowers/plans/2026-05-10-notifications-overhaul.md (local)