Backend: Add multi-language campaign metadata support

[joelpeace48-cell]

Summary

Campaigns targeting non-English audiences need localized name and description fields. The backend should store translations alongside the default English content and serve the appropriate locale based on the Accept-Language header.

Acceptance Criteria

• Add translations JSON column to campaigns table: { 'es': { name, description }, 'fr': { name, description } }
• Add PUT /api/v1/campaigns/:id/translations/:locale — upsert a translation (API key required); validate locale is BCP-47 format (e.g. es, fr, zh-CN)
• Add GET /api/v1/campaigns/:id/translations — return all stored translations
• Locale negotiation: GET /api/v1/campaigns and GET /api/v1/campaigns/:id serve translated name/description based on Accept-Language header; fallback to en if translation unavailable
• Add ?locale=es query param override for explicit locale selection
• Add available_locales array to campaign response listing which locales have translations
• Limit: max 10 locales per campaign, each translation max 2KB
• Unit tests: locale negotiation, fallback to English, CRUD translations

References

• backend/src/schemas.js
• backend/src/dal/sqliteCampaignRepository.js

[heymide]

@heymide has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I can take this on. I've gone through the details and will provide a well-tested solution aligned with the project standards.

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[sadiqabubakar826-del]

@sadiqabubakar826-del has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

have gone through this kindly assign this to me

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[rahimatonize]

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Hi maintainer, I would love to work on this issue please assign

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[Wilfred007]

@Wilfred007 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Can I work on this task?

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Congratulations, @Wilfred007! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

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[grantfox-oss]

🦊 GrantFox — @Wilfred007 has been assigned to this issue as part of the Official Campaign campaign!

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign campaign!

@Wilfred007's PR #717 was approved and merged by @joelpeace48-cell.

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👏 Great work, @Wilfred007! Keep contributing to FinesseStudioLab.

[drips-wave]

This issue has been completed by @Wilfred007 as part of the Stellar Wave Program's 6th Wave 🥳

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