Add site asset CSV import with fuzzy reconciliation

Sites seed inventory from the Asset Collector script or spreadsheet exports, but lookup names drift between sources (Dell vs Dell Inc.), which would otherwise create duplicate vendors/models/types on every import. The importer now normalizes and fuzzy-matches near-miss references onto existing lookup rows within an operator-set similarity threshold, auto-applying the match while reporting it for review so nothing merges silently. Operating systems and asset rows are never reconciled. Adds the dedicated Import Site Assets page with script/template download and a multi-file dry-run/commit workflow.

frontend/src/router/routes/core.js

@@ -150,6 +150,12 @@ export default [
     component: () => import('../../views/settings/BrandingSettings.vue'),
     meta: { requiresAuth: true, requiresAdmin: true }
   },
+  {
+    path: 'settings/importsiteassets',
+    name: 'import-site-assets',
+    component: () => import('../../views/settings/ImportSiteAssets.vue'),
+    meta: { requiresAuth: true, requiresAdmin: true }
+  },
   {
     path: 'settings/printing',
     name: 'printing-settings',