feat: relocate import tools into studio and harden catalog/furnidata integrity

- Move /admin/import/* tools under /admin/studio/* and add studio nav, layout and tabs
- Add shared catalog maintenance panel plus a /admin/studio/maintenance tab
- Make furnidata reconciliation overwrite conflicting entries with the
  DB-authoritative items_base classname/id (surfaced via fixedConflicts)
- Add furnidata_translate_enabled setting to skip the heavy localized
  furnidata build during import (manual build-languages still forces it)
- Update staff smoke contract test for the studio hub

src/lib/admin-nav.ts

@@ -13,7 +13,6 @@ import {
 	Gavel,
 	HelpCircle,
 	Image,
-	Import,
 	KeyRound,
 	Languages,
 	LayoutDashboard,
@@ -35,7 +34,6 @@ import {
 	Terminal,
 	Ticket,
 	Trophy,
-	Upload,
 	Users,
 	UsersRound,
 	Volume2,
@@ -219,38 +217,6 @@ export const ADMIN_HUBS: AdminHubDefinition[] = [
 			{ href: "/admin/devops/errors", labelKey: "errors" },
 		],
 	},
-	{
-		id: "import",
-		titleKey: "import",
-		subtitleKey: "importSubtitle",
-		icon: Upload,
-		prefixes: ["/admin/import"],
-		tabs: [
-			{
-				href: "/admin/import",
-				labelKey: "importOverview",
-				match: ["/admin/import"],
-			},
-			{ href: "/admin/import/badges", labelKey: "importBadges" },
-			{
-				href: "/admin/import/furni/upload",
-				labelKey: "importUpload",
-				match: ["/admin/import/furni/upload"],
-			},
-			{
-				href: "/admin/import/furni",
-				labelKey: "importFurni",
-				match: ["/admin/import/furni"],
-			},
-			{ href: "/admin/import/clothing", labelKey: "importClothing" },
-			{ href: "/admin/import/effects", labelKey: "importEffects" },
-			{ href: "/admin/import/pets", labelKey: "importPets" },
-			{ href: "/admin/import/clone", labelKey: "importClone" },
-			{ href: "/admin/import/sync", labelKey: "importSync" },
-			{ href: "/admin/import/repair-icons", labelKey: "importRepairIcons" },
-			{ href: "/admin/import/audit", labelKey: "importAudit" },
-		],
-	},
 ];
 
 /** Longest-prefix match so nested routes (e.g. /admin/logs/audit) win. */
@@ -637,13 +603,6 @@ export const ADMIN_NAV_GROUPS: AdminNavGroup[] = [
 				permission: PERMS.ASSETS_IMPORT,
 				matchPrefixes: ["/admin/studio"],
 			},
-			{
-				href: "/admin/import",
-				labelKey: "import",
-				icon: Import,
-				permission: PERMS.ASSETS_IMPORT,
-				matchPrefixes: ["/admin/import"],
-			},
 			{
 				href: "/admin/translations",
 				labelKey: "translations",