docs: remove admin SPA references and update production URLs

The admin SPA (apps/admin/) has been retired. Its functionality now
lives in apps/app/ under /platform/* routes for super_admin users.
Updated all documentation to reflect: 2 SPAs instead of 3, removed
FRONTEND_ADMIN_URL/port 5173 references, changed production URL from
app.crewli.app to crewli.app. Retired admin-specific security audit
findings (A13-2, A13-4, A13-5, A13-7) and APPS-01 backlog item.

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

dev-docs/MASTER_PROMPT_CC.md

@@ -17,9 +17,8 @@ Crewli is a multi-tenant SaaS platform for event and festival management.
 
 - **Backend:** Laravel 12 REST API (no Blade views, no Inertia), Sanctum auth,
   Spatie Permission, MySQL 8, Redis
-- **Frontend:** Three standalone Vue 3 + TypeScript SPAs on Vuexy 9.5 /
-  Vuetify 3.10 — `apps/admin/` (port 5173), `apps/app/` (port 5174),
-  `apps/portal/` (port 5175)
+- **Frontend:** Two standalone Vue 3 + TypeScript SPAs on Vuexy 9.5 /
+  Vuetify 3.10 — `apps/app/` (port 5174), `apps/portal/` (port 5175)
 - **State:** Pinia + TanStack Vue Query
 - **Forms:** VeeValidate + Zod
 - **API base path:** `/api/v1/`
@@ -47,8 +46,7 @@ crewli/
 │   │   └── seeders/
 │   └── tests/Feature/Api/V1/
 ├── apps/
-│   ├── admin/                    # Super Admin SPA
-│   ├── app/                      # Organizer SPA (main app)
+│   ├── app/                      # Organizer + Platform Admin SPA (main app)
 │   │   └── src/
 │   │       ├── lib/axios.ts      # THE ONLY axios instance
 │   │       ├── composables/api/  # TanStack Query composables