fix : added colored tier indicators to achievement notification emails

[tmdeveloper007]

What does this PR do?

Removes emoji characters from achievement unlock notification emails by replacing TIER_EMOJI with TIER_COLORS.

Summary of What Has Been Done

Replaced TIER_EMOJI usage in src/lib/notification-senders/achievement.ts with TIER_COLORS from the same module. Tier indicators are now rendered as colored circles (HTML span elements with border-radius and background-color) instead of emoji characters.

Changes Made

• src/lib/notification-senders/achievement.ts:
  • Changed import from TIER_EMOJI to TIER_COLORS from ../achievements
  • Replaced const emoji = TIER_EMOJI[a.tier] ?? "" with const tierColor = TIER_COLORS[a.tier] ?? "#888888"
  • Updated HTML list item to render a colored circle span instead of an emoji character

Impact it Made

• Achievement unlock emails no longer contain emoji characters
• Tier information remains visually communicated through color-coded indicators
• All notification code now complies with the project-wide no-emoji policy

Closes 1383

Note: Please assign this PR to the tmdeveloper007 account.

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[Ixotic27]

LGTM! Verified and approved. Great contribution!

[Ixotic27]

LGTM! Approved and verified. Great contribution!

[github-actions]

🎉 Congratulations @tmdeveloper007! Your PR has been successfully merged. 🚀

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