feat(provisioning): tenant data model + CRUD with JWT-validated authz

Implements Phase 3 from docs/NEXT-STEPS.md.

Mongoose schemas (services/provisioning/src/schemas/):
- Tenant: slug, name, status, plan, domains, billingInfo, plus handles for
  Authentik group, OCIS space, and Stalwart domain (set in Phase 4)
- User: authentikSubjectId, tenantIds[], email, name, role, platformAdmin flag
- Subscription: tenantId, plan, status, Stripe IDs (unused until Phase 4)

Auth (services/provisioning/src/auth/):
- JwtAuthGuard verifies Authentik access tokens against the provider's JWKS
  with issuer + audience checks. Uses NODE_EXTRA_CA_CERTS to trust the
  mkcert root for the local Authentik cert
- ActorService resolves the verified JWT into a Mongo User document — every
  controller reads tenantIds + platformAdmin from the DB, not the token
- CurrentUser decorator extracts the JWT payload onto controllers

CRUD modules:
- /tenants, /users, /subscriptions with create/read/update/delete
- /users/me upserts the caller's User record on every request, syncing email,
  name, tenantIds, and platformAdmin from the JWT's groups claim — the only
  place we read JWT.groups outside the bootstrap

Why DB-derived authz: putting all group memberships in the JWT doesn't scale
past ~50 tenants per user (header/cookie size limits, no mid-session
revocation, stale data until re-login). JWT now carries identity only; the
DB is the source of truth for who can see what.

Seed (SeedService.OnApplicationBootstrap): idempotent creation of the
default 'dezky' tenant + matching subscription. User records are created on
first /users/me hit.

Infrastructure:
- Traefik label exposes provisioning at https://api.dezky.local (dev only)
- api.dezky.local added to Docker network aliases on Traefik
- mkcert root CA mounted into the provisioning container for JWKS fetch
- Authentik 'groups' scope mapping created + attached to dezky-portal
  provider; portal now requests it as a scope
- nuxt.config.ts portal: exposeAccessToken=true so Nitro forwards token;
  NUXT_OIDC_TOKEN_KEY fixed to base64-encoded 32 bytes (was hex, causing
  "Invalid key length" once exposeAccessToken turned on)

Portal: apps/portal/server/api/me.get.ts is a scaffolding route that
forwards the user's access token to provisioning and returns profile +
tenants + subscriptions — verifies the full chain end to end.

infrastructure/docker-compose/docker-compose.yml

@@ -54,6 +54,7 @@ services:
           - traefik.dezky.local
           - auth.dezky.local
           - app.dezky.local
+          - api.dezky.local
           - files.dezky.local
           - mail.dezky.local
           - office.dezky.local
@@ -331,11 +332,23 @@ services:
       STALWART_ADMIN_USER: admin
       STALWART_ADMIN_PASSWORD: ${STALWART_ADMIN_PASSWORD}
       OCIS_API_URL: http://ocis:9200
+      # JWT validation against Authentik for portal-issued access tokens
+      AUTHENTIK_ISSUER: https://auth.dezky.local/application/o/dezky-portal/
+      AUTHENTIK_AUDIENCE: dezky-portal
+      AUTHENTIK_JWKS_URI: https://auth.dezky.local/application/o/dezky-portal/jwks/
+      # Trust mkcert root CA for Node fetch (dev only)
+      NODE_EXTRA_CA_CERTS: /etc/ssl/mkcert-root.pem
     volumes:
       - ../../services/provisioning:/app
       - provisioning_node_modules:/app/node_modules
+      - ./certs/mkcert-root.pem:/etc/ssl/mkcert-root.pem:ro
     networks: [dezky]
     depends_on:
       mongo:
         condition: service_healthy
+    labels:
+      - traefik.enable=true
+      - traefik.http.routers.api.rule=Host(`api.dezky.local`)
+      - traefik.http.routers.api.tls=true
+      - traefik.http.services.api.loadbalancer.server.port=3001