test(dashboard): add partial-failure resilience test + fix i18n Dok. key

- page.server.spec.ts: new test verifies topPersons=[] when that fetch
  rejects, rest of reader data still loads — addresses @Sara concern
- ReaderPersonChips: replaces hardcoded "Dok." with
  dashboard_reader_doc_count_suffix Paraglide key (de/en/es)
  — addresses @Felix suggestion

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/messages/de.json

@@ -460,6 +460,7 @@
 	"dashboard_badge_new": "Neu",
 	"dashboard_badge_updated": "Aktualisiert",
 	"dashboard_reader_all_stories": "Alle Geschichten →",
+	"dashboard_reader_doc_count_suffix": "Dok.",
 	"dashboard_resume_label": "Zuletzt geöffnet:",
 	"dashboard_resume_fallback": "Unbekanntes Dokument",
 	"doc_status_placeholder": "Platzhalter",

frontend/messages/en.json

@@ -460,6 +460,7 @@
 	"dashboard_badge_new": "New",
 	"dashboard_badge_updated": "Updated",
 	"dashboard_reader_all_stories": "All Stories →",
+	"dashboard_reader_doc_count_suffix": "docs.",
 	"dashboard_resume_label": "Last opened:",
 	"dashboard_resume_fallback": "Unknown document",
 	"doc_status_placeholder": "Placeholder",

frontend/messages/es.json

@@ -460,6 +460,7 @@
 	"dashboard_badge_new": "Nuevo",
 	"dashboard_badge_updated": "Actualizado",
 	"dashboard_reader_all_stories": "Todas las historias →",
+	"dashboard_reader_doc_count_suffix": "docs.",
 	"dashboard_resume_label": "Último abierto:",
 	"dashboard_resume_fallback": "Documento desconocido",
 	"doc_status_placeholder": "Marcador",