feat: add database backed membership tiers

docs/TASKS/organizations/008-database-backed-membership-tiers.md

@@ -0,0 +1,51 @@
+# Task: Database-backed organization membership tiers
+
+## Feature Spec
+
+`docs/FEATURES/organizations.md`
+
+## Goal
+
+Move organization membership tiers and usage limits out of frontend/static logic and into the database so an organization owner can select a tier immediately, before payment-provider integration exists.
+
+## Scope
+
+- Add a persisted membership tier model with seeded tiers and limits.
+- Add an active membership tier relationship on `Organization`.
+- Add backend APIs to list available tiers and change an organization's active tier.
+- Let organization creation select an initial tier, defaulting to Free.
+- Show the current tier and tier selector on organization usage settings.
+- Regenerate OpenAPI contracts after backend changes.
+
+## Likely Files
+
+- `backend/src/Socialize.Api/Modules/Organizations/Data/*`
+- `backend/src/Socialize.Api/Modules/Organizations/Handlers/*`
+- `backend/src/Socialize.Api/Migrations/*`
+- `frontend/src/features/organizations/stores/organizationStore.js`
+- `frontend/src/features/organizations/views/OrganizationOnboardingView.vue`
+- `frontend/src/features/organizations/views/OrganizationSettingsView.vue`
+- `frontend/src/locales/en.json`
+- `frontend/src/locales/fr.json`
+- `shared/openapi/openapi.json`
+- `frontend/src/api/schema.d.ts`
+
+## Validation
+
+```bash
+dotnet ef migrations add AddOrganizationMembershipTiers --project backend/src/Socialize.Api/Socialize.Api.csproj --startup-project backend/src/Socialize.Api/Socialize.Api.csproj
+dotnet build backend/Socialize.slnx
+dotnet test backend/Socialize.slnx
+cd frontend && npm run build
+./scripts/update-openapi.sh
+```
+
+## Done When
+
+- [x] Membership tiers and limits are database-backed.
+- [x] Organizations persist their selected membership tier.
+- [x] Organization owners/billing managers can change tiers from the usage settings page.
+- [x] New organizations can choose an initial tier.
+- [x] Usage limits come from the selected tier, not organization name or frontend constants.
+- [x] EF migration is generated with `dotnet ef migrations add`.
+- [x] OpenAPI and frontend schema are regenerated.