* ♻️ use Single Responsibility Principle on brains_subscription
* ✨ new brain subscription endpoints for invited user
* 📝 add documentation to endpoints
* 🎨 add base_frontend_url to send custom url for brain share
* ✏️ brains instead of brain in url
* ✨ use origin in header for frontend url in subscription email
* 🚚 move and remove unused code
* ✨ new subscription API for BE endpoints in frontend
* ✨ new addBrain to add a shared brain in frontend
* 🥚 new hook for brain invitations
* ✨ new page for brain invitation
* ✨ change frontend url to copy for brain subscription
* ✏️ call RBAC with wrapper function
* ✏️ last typos
* refactor(MultipleBrain): separate providing and data fetching
* refactor(MultipleBrain): update useBrainApi
* feat(MultipleBrains): remove unnecessary data fetchings
* test(useBrainApi): update unit tests
* 🗑️ remove date input from fetch_user_id_from_credentials
* ♻️ refactor backend utils by splitting it into files
* 💡 comments for next actions to update /upload
* 🚚 move SupabaseProvider tp libs
* 🚚 move useAxios to hooks
* ♻️ refacto brain routes
* 🚨 update lintermfor paths
* ✨ new brain context provider
* ✨ new brain component in navbar
* 🚨 fix linter and async
* 🇸🇪 add feature flag for multiple-brains
