[Backend] -- Implement Challenge System with Gamification

[Devsol-01]

Description:
Enhance challenges module with achievement tracking, leaderboards, and reward distribution for user engagement.

Acceptance Criteria:

• Design challenge framework
• Implement achievement tracking
• Create leaderboard system
• Add reward distribution
• Implement challenge progression
• Add challenge notifications
• Create challenge analytics

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[coderolisa]

@coderolisa has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hello maintainer let me work on this
please assign

ℹ️ Repo Maintainers: To accept this application, review their application or assign @coderolisa to this issue.

[dot-enny]

@dot-enny has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi there, i think i can handle this.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @dot-enny to this issue.

[charliechinedu19-netizen]

@charliechinedu19-netizen has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

hey gm, i'd love to take on this issue real quick

ℹ️ Repo Maintainers: To accept this application, review their application or assign @charliechinedu19-netizen to this issue.

[faith3310]

@faith3310 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

i would love to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @faith3310 to this issue.

[drips-wave]

Congratulations, @faith3310! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @faith3310: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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