New table to store challenge configuration

[raphodn]

What

After launching the first challenge in the frontend, and if we wish to launch more challenges in the future, then we need to start storing the data in the backend.

Related issues & discussions

• A page for community challenges 🏆  open-prices-frontend#934
• Community challenges #509

[TTalex]

What needs to be stored for UI

• challenge_id (Autoincrement)
• state ("Upcoming", "Currently Running", "Archived". To filter which ones to display by default or hide)
• title (example: "Nutella")
• icon (example: "🌰", could be part of title)
• subtitle (example: "(and other hazelnut spreads)", could be part of title)
• startDate (example: "2025-01-20")
• endDate (example: "2025-02-20")
• categories (example: ["en:hazelnut-spreads"])
• exampleProofUrl (example: "https://prices.openfoodfacts.org/img/0029/nCWeCVnpQJ.webp")

Bonus at the end of challenge

• Rankings, top contributors according to
  • Overall pictures uploaded
  • Price tags photographed
  • Prices added
• Stats
  • Total number of prices added (could be computed on the fly, as currently done on frontend)
  • Total number of pictures (could be computed on the fly, as currently done on frontend)
  • Total number of contributors
• Reuses/articles links
• Source (I guess it could be interesting to keep track of where the challenge idea came from, if it was linked to an event like OFF Days for example)