fix(core): resolve local client url redirects and stabilize dev environment

- enforce localhost:5174 for wheel campaign client URL in local development
- lock vite dev server ports using strictPort on admin (5173) and client (5174)
- sanitize .env.example and remove hardcoded staging domain
- configure root dev orchestration and docker multi-stage build context

apps/admin/vite.config.ts

@@ -12,6 +12,7 @@ export default defineConfig({
   },
   server: {
     port: 5173,
+    strictPort: true,
     proxy: {
       '/api': {
         target: 'http://localhost:3000',