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/AppLayout.vue

@@ -25,8 +25,8 @@
         </template>
 
         <div class="nav-section">Displays</div>
-        <a href="/shopfloor" target="_blank" class="external-link">Shopfloor Dashboard</a>
-        <a href="/tv" target="_blank" class="external-link">TV Slideshow</a>
+        <a :href="withBase('/shopfloor')" target="_blank" class="external-link">Shopfloor Dashboard</a>
+        <a :href="withBase('/tv')" target="_blank" class="external-link">TV Slideshow</a>
 
         <router-link v-if="authStore.isAdmin" to="/settings">Settings</router-link>
       </nav>
@@ -107,6 +107,7 @@ import { useAuthStore } from '../stores/auth'
 import { currentTheme, toggleTheme } from '../stores/theme'
 import { dashboardApi, notificationsApi } from '../api'
 import { getFacilityName, getSiteLogo, getServicenowUrls } from '../utils/siteSettings'
+import { withBase } from '../utils/basePath'
 
 const router = useRouter()
 const route = useRoute()
@@ -118,7 +119,7 @@ const searchQuery = ref('')
 const navItems = ref([])
 const activeNotifications = ref([])
 const facilityName = ref('ShopDB')
-const siteLogo = ref('/ge-aerospace-logo.svg')
+const siteLogo = ref(withBase('/ge-aerospace-logo.svg'))
 const servicenowConfig = ref({ enabled: true, searchUrl: '' })
 
 function getTicketSearchUrl(ticketnumber) {