i18n(scanner): translate the scoped-scan strings

The scoped-scan feature left exactly 6 [TODO: Translate] keys behind, so this
is the whole pending set for all 9 locales. Renderings reuse the established
nouns (folder: zh-CN 文件夹 / ja フォルダ / ru папка / he תיקייה; "model" counts
from sidebar.deleteFolderModal) and introduce one new term, "Offline" for a
configured root that cannot be read right now:

  scopeSection        zh-CN 只扫描一个文件夹 · ja フォルダを 1 つだけスキャン
                      fr Analyser un seul dossier · ru Сканировать только одну папку
  rootOffline         zh-CN 离线 · ja オフライン · fr Hors ligne · ru Недоступен
  rootModels          zh-CN {count} 个模型 · ko 모델 {count}개 · he {count} מודלים
  refreshCompleteScoped / refreshKeptUnreachable / scanRootUnreachable
                      (counts and {scope}/{paths} stay verbatim)

Every placeholder set matches en.json, fr keeps the typographic apostrophe, and
the three CJK locales keep full-width punctuation while ko uses ASCII like the
rest of that file. docs/i18n-translation-guidelines.md gains the
"Scoped scan and root availability" terminology table plus the updated status
note, so the "no remaining placeholders" claim holds again.

Verified: python scripts/sync_translation_keys.py --dry-run reports no pending
changes, pytest tests/i18n 20 passed, and grep -c "TODO: Translate"
locales/*.json is 0 everywhere.

locales/es.json

@@ -919,9 +919,9 @@
                 "title": "Actualizar lista de modelos",
                 "full": "Reconstruir caché",
                 "fullTooltip": "Vuelve a cargar todos los detalles desde los archivos de metadatos; úsalo si la biblioteca parece desactualizada o tras ediciones manuales.",
-                "scopeSection": "[TODO: Translate] Scan one folder",
-                "rootOffline": "[TODO: Translate] Offline",
-                "rootModels": "[TODO: Translate] {count} models"
+                "scopeSection": "Escanear solo una carpeta",
+                "rootOffline": "Sin conexión",
+                "rootModels": "{count} modelos"
             },
             "fetch": {
                 "title": "Obtener metadatos de CivitAI",
@@ -2808,9 +2808,9 @@
             "moveFailed": "No se pudo mover el elemento: {message}",
             "copiedToClipboard": "Copiado al portapapeles",
             "downloadStarted": "Descarga iniciada",
-            "refreshCompleteScoped": "[TODO: Translate] Scanned {scope}: {added} new, {removed} removed",
-            "refreshKeptUnreachable": "[TODO: Translate] {count} models kept: {paths} not reachable",
-            "scanRootUnreachable": "[TODO: Translate] {scope} is not reachable right now. Nothing was changed."
+            "refreshCompleteScoped": "{scope} escaneado: {added} nuevo(s), {removed} eliminado(s)",
+            "refreshKeptUnreachable": "{count} modelos conservados: {paths} no accesible(s)",
+            "scanRootUnreachable": "{scope} no es accesible ahora mismo. No se ha cambiado nada."
         },
         "agent": {
             "llmNotConfigured": "Proveedor de IA no configurado. Actívelo en Configuración → Proveedor de IA.",