Convert notification messages to use Ember Intl translation keys

[Copilot]

This PR implements the requested change to use Ember Intl style translation keys for notification messages instead of hardcoded English strings, enabling proper internationalization support for the frontend application.

Changes Made

Database Schema

• Added migration to create message_key (string) and message_params (jsonb) columns on the notifications table
• Added missing badge award types to the notification enum: dragionfruit_badge_award, blueberrinies_badge_award, beamsprout_badge_award

Notification Model

Completely refactored the set_message method to use structured translation keys:

Before:

when "strawberry_badge_award"
  "#{self.user.username} got the strawbur badge!"

After:

when "strawberry_badge_award"
  set_translation_key("notifications.badge_award.strawberry", { username: self.user.username })

API Response

Updated the NotificationSerializer to include the new fields:

• message_key: Translation key (e.g., "notifications.badge_award.strawberry")
• message_params: Parameters for interpolation (e.g., { "username": "mcfiredrill" })
• message: Kept for backward compatibility (empty for new notifications)

Translation Key Structure

All notification types now use consistent dot-separated keys:

• Badge awards: notifications.badge_award.{fruit_type}
• User progress: notifications.level_up, notifications.experience_point_award
• Fruit tickets: notifications.fruit_ticket_gift, notifications.supporter_fruit_ticket_stipend
• Content events: notifications.new_thread, notifications.wiki_page_update
• Shrimpo events: notifications.shrimpo_started, notifications.shrimpo_entry

Frontend Integration

The frontend app can now use these translation keys with Ember Intl:

const translatedMessage = this.intl.t(notification.message_key, notification.message_params);

Backward Compatibility

• Existing notifications retain their original English messages in the message field
• New notifications have empty message field but populated message_key and message_params
• Frontend should prioritize translation keys when available, fallback to legacy message field

Documentation

Added comprehensive documentation in docs/notification_translations.md listing all translation keys and their required parameters for the frontend team.

Testing

Created test coverage for the new translation key functionality to ensure proper key assignment and parameter extraction.

Fixes the internationalization requirement by moving message composition to the frontend where proper translation management can be handled by the datafruits/datafruits application.

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