feat(localization): expand language support and enhance UI for user settings

- Added support for additional UI locales including Cebuano and Spanish, improving accessibility for a broader user base.
- Updated language selection components in the AppHeader and SettingsWidget to reflect new language options, enhancing user experience.
- Enhanced localization of various UI elements across components, ensuring consistent language representation and improved user engagement.
- Implemented logic to synchronize user language preferences with backend settings, providing a seamless experience when changing languages.

frontend/src/i18n/locales/es/general.json

@@ -41,6 +41,59 @@
     "message": {
         "close": "Cerrar"
     },
+    "appShell": {
+        "header": {
+            "tagline": "Plataforma comunitaria",
+            "beta": "Beta",
+            "backend": "Backend",
+            "daemon": "Daemon",
+            "language": "Idioma"
+        },
+        "footer": {
+            "systemLabel": "Sistema",
+            "noOpenDialogs": "No hay diálogos abiertos",
+            "activeWindows": "{count} ventanas activas",
+            "systemReady": "Sistema listo",
+            "systemStatusUnavailable": "El estado del sistema no está disponible directamente en esta vista en este momento."
+        }
+    },
+    "widgets": {
+        "dashboard": {
+            "dragHandle": "Mover",
+            "loading": "Cargando..."
+        },
+        "birthdays": {
+            "today": "¡Hoy!",
+            "tomorrow": "Mañana",
+            "turningAge": "(cumple {age})",
+            "inDays": "{count} días",
+            "empty": "No hay cumpleaños visibles de amigos"
+        },
+        "upcoming": {
+            "today": "Hoy",
+            "tomorrow": "Mañana",
+            "timeAt": "{time} h",
+            "allDay": "Todo el día",
+            "empty": "No hay citas próximas"
+        },
+        "appointments": {
+            "title": "📅 Citas",
+            "loading": "Cargando citas...",
+            "empty": "No hay citas próximas",
+            "loadError": "No se pudieron cargar las citas"
+        },
+        "list": {
+            "noEntries": "No hay entradas",
+            "entriesCount": "({count} entradas)",
+            "fieldsCount": "({count} campos)"
+        },
+        "news": {
+            "emptyValue": "—"
+        },
+        "falukant": {
+            "emptyValue": "—"
+        }
+    },
     "gender": {
         "male": "Masculino",
         "female": "Femenino",