Support subpath IIS deployment as a second install method

The app can run as an IIS Application under an existing site
(e.g. https://host/ops/) instead of its own site + port:

- frontend: vite base via VITE_BASE_PATH; router history, axios
  baseURL, and root-absolute asset/route paths resolve through
  utils/basePath.js withBase()
- backend: MOUNT_PATH (env or .env) wraps the app in a WSGI
  middleware that shifts the prefix into SCRIPT_NAME, so one knob
  serves API + SPA under the mount
- docs: INSTALL-WINDOWS-IIS.md section 7b runbook + troubleshooting
  rows; DEPLOY-WINDOWS-IIS.md pointer; commented examples in
  deploy/windows/web.config and .env.example

Root deployment unchanged (MOUNT_PATH unset, base '/'). Also folds
two stray root-absolute callers into the shared plumbing
(MachineForm relationship-types fetch, reports CSV window.open).

frontend/src/views/ChangePassword.vue

@@ -41,6 +41,7 @@ import { useRouter } from 'vue-router'
 import { useAuthStore } from '../stores/auth'
 import { authApi } from '../api'
 import { getSiteLogo } from '../utils/siteSettings'
+import { withBase } from '../utils/basePath'
 import { apiError } from '../utils/apiError'
 
 const router = useRouter()
@@ -48,7 +49,7 @@ const authStore = useAuthStore()
 
 const forced = computed(() => authStore.mustChangePassword)
 
-const siteLogo = ref('/ge-aerospace-logo.svg')
+const siteLogo = ref(withBase('/ge-aerospace-logo.svg'))
 const currentPassword = ref('')
 const newPassword = ref('')
 const confirmPassword = ref('')