feat: consolidate frontend API layer, add query-client, and harden backend Fase 1

Frontend:
- Consolidate duplicate API layers into single src/lib/axios.ts per app
- Remove src/lib/api-client.ts and src/utils/api.ts (admin)
- Add src/lib/query-client.ts with TanStack Query config per app
- Update all imports and auto-import config

Backend:
- Fix organisations.billing_status default to 'trial'
- Fix user_invitations.invited_by_user_id to nullOnDelete
- Add MeResource with separated app_roles and pivot-based org roles
- Add cross-org check to EventPolicy view() and update()
- Restrict EventPolicy create/update to org_admin/event_manager (not org_member)
- Attach creator as org_admin on organisation store
- Add query scopes to Event and UserInvitation models
- Improve factories with Dutch test data
- Expand test suite from 29 to 41 tests (90 assertions)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/Http/Requests/Api/V1/StoreOrganisationRequest.php

@@ -19,7 +19,7 @@ final class StoreOrganisationRequest extends FormRequest
         return [
             'name' => ['required', 'string', 'max:255'],
             'slug' => ['required', 'string', 'max:255', 'unique:organisations,slug', 'regex:/^[a-z0-9-]+$/'],
-            'billing_status' => ['sometimes', 'string', 'in:active,trial,suspended'],
+            'billing_status' => ['sometimes', 'string', 'in:trial,active,suspended,cancelled'],
             'settings' => ['sometimes', 'array'],
         ];
     }