Add sunset tracking endpoint for keys approaching inactivity threshold

[Chucks1093]

Summary

Build an endpoint that returns creator keys approaching or reaching the inactivity sunset threshold, with days since last trade and sunset status.

Scope

• GET /keys/sunset-watch returns all keys with sunset_pending or near-threshold status
• Days since last trade calculated per key from trade records
• Sunset threshold read from contract configuration
• Admin-only endpoint for monitoring
• Keys sorted by inactivity duration descending

Acceptance Criteria

• Keys listed with correct days since last trade
• sunset_pending status reflected for flagged keys
• Keys sorted by inactivity duration correctly
• Admin-only access enforced via role middleware
• Response updates within one sync cycle of new KeySunsetFlagged event

ETA

12 hours

[Nexus00031]

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[TheHalalHunter]

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Hi maintainer
I’d love to help out with this issue. I’ve checked the current codebase/documentation and know exactly what needs to be updated to make this clearer. I will ensure everything aligns perfectly with your existing contribution guidelines.

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[JemimahEkong]

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[DevScoopee]

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I fully understand what needs to be done and can deliver. Kindly assign

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@TheHalalHunter's PR #973 was approved and merged by @Chucks1093.

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👏 Great work, @TheHalalHunter! Keep contributing to accesslayerorg.

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