feat(studio): expand nitro cleanup with repair, auto-clean, and orphaned assets

Scan distinguishes fake, broken, and orphaned SWF/icon assets with age
metadata, deletes per asset kind, re-downloads broken nitro bundles from
configured sources, auto-cleans old fake leftovers, and exports a JSON
manifest. Adds rebuild and auto-clean API endpoints with audit coverage
and a housekeeping preview route under the hotel domain.

Verified: full vitest suite (2213 tests), typecheck, and biome all pass.

src/messages/en.json

@@ -4771,7 +4771,13 @@
 				},
 				"hotel": {
 					"title": "Hotel",
-					"description": "Rooms, radio, and asset tools"
+					"description": "Rooms, radio, and asset tools",
+					"routes": {
+						"nitroCleanup": {
+							"title": "Nitro cleanup",
+							"description": "Scan and remove fake, broken, and orphaned furni asset files"
+						}
+					}
 				},
 				"system": {
 					"title": "System",

src/messages/it.json

@@ -4770,7 +4770,13 @@
 				},
 				"hotel": {
 					"title": "Hotel",
-					"description": "Stanze, radio e strumenti per gli asset"
+					"description": "Stanze, radio e strumenti per gli asset",
+					"routes": {
+						"nitroCleanup": {
+							"title": "Pulizia nitro",
+							"description": "Scansiona e rimuovi i file asset furni falsi, danneggiati o orfani"
+						}
+					}
 				},
 				"system": {
 					"title": "Sistema",