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/src/vite-env.d.ts

@@ -0,0 +1,9 @@
+/// <reference types="vite/client" />
+
+interface ImportMetaEnv {
+  readonly VITE_CLIENT_PUBLIC_URL?: string;
+}
+
+interface ImportMeta {
+  readonly env: ImportMetaEnv;
+}