Add default category icon and improve visit display:

- Set default icon for empty category in AdventureModal
- Enhance layout for visit buttons and validation messages in DateRangeCollapse
- Update localization files to include "no visits" strings in multiple languages

frontend/src/locales/de.json

@@ -256,7 +256,8 @@
     "additional_info": "Weitere Informationen",
     "invalid_date_range": "Ungültiger Datumsbereich",
     "sunrise_sunset": "Sonnenaufgang",
-    "timezone": "Zeitzone"
+    "timezone": "Zeitzone",
+    "no_visits": "Keine Besuche"
   },
   "home": {
     "desc_1": "Entdecken, planen und erkunden Sie mühelos",

frontend/src/locales/en.json

@@ -64,6 +64,7 @@
 		"collection_link_success": "Adventure linked to collection successfully!",
 		"invalid_date_range": "Invalid date range",
 		"timezone": "Timezone",
+		"no_visits": "No visits",
 		"no_image_found": "No image found",
 		"collection_link_error": "Error linking adventure to collection",
 		"adventure_delete_confirm": "Are you sure you want to delete this adventure? This action cannot be undone.",

frontend/src/locales/es.json

@@ -304,7 +304,8 @@
     "additional_info": "información adicional",
     "invalid_date_range": "Rango de fechas no válido",
     "sunrise_sunset": "Amanecer",
-    "timezone": "Zona horaria"
+    "timezone": "Zona horaria",
+    "no_visits": "No hay visitas"
   },
   "worldtravel": {
     "all": "Todo",

frontend/src/locales/fr.json

@@ -256,7 +256,8 @@
     "additional_info": "Informations Complémentaires",
     "invalid_date_range": "Plage de dates non valide",
     "sunrise_sunset": "Lever du soleil",
-    "timezone": "Fuseau horaire"
+    "timezone": "Fuseau horaire",
+    "no_visits": "Pas de visites"
   },
   "home": {
     "desc_1": "Découvrez, planifiez et explorez en toute simplicité",

frontend/src/locales/it.json

@@ -256,7 +256,8 @@
     "additional_info": "Ulteriori informazioni",
     "invalid_date_range": "Intervallo di date non valido",
     "sunrise_sunset": "Alba",
-    "timezone": "Fuso orario"
+    "timezone": "Fuso orario",
+    "no_visits": "Nessuna visita"
   },
   "home": {
     "desc_1": "Scopri, pianifica ed esplora con facilità",

frontend/src/locales/ko.json

@@ -256,7 +256,8 @@
     "additional_info": "추가 정보",
     "invalid_date_range": "잘못된 날짜 범위",
     "sunrise_sunset": "해돋이",
-    "timezone": "시간대"
+    "timezone": "시간대",
+    "no_visits": "방문 없음"
   },
   "auth": {
     "both_passwords_required": "두 암호 모두 필요합니다",

frontend/src/locales/nl.json

@@ -256,7 +256,8 @@
     "additional_info": "Aanvullende informatie",
     "invalid_date_range": "Ongeldige datumbereik",
     "sunrise_sunset": "Zonsopgang",
-    "timezone": "Tijdzone"
+    "timezone": "Tijdzone",
+    "no_visits": "Geen bezoeken"
   },
   "home": {
     "desc_1": "Ontdek, plan en verken met gemak",

frontend/src/locales/no.json

@@ -304,7 +304,8 @@
     "no_ordered_items": "Legg til varer med datoer i samlingen for å se dem her.",
     "ordered_itinerary": "Bestilt reiserute",
     "sunrise_sunset": "Soloppgang",
-    "timezone": "Tidssone"
+    "timezone": "Tidssone",
+    "no_visits": "Ingen besøk"
   },
   "worldtravel": {
     "country_list": "Liste over land",

frontend/src/locales/pl.json

@@ -304,7 +304,8 @@
     "additional_info": "Dodatkowe informacje",
     "invalid_date_range": "Niepoprawny zakres dat",
     "sunrise_sunset": "Wschód słońca",
-    "timezone": "Strefa czasowa"
+    "timezone": "Strefa czasowa",
+    "no_visits": "Brak wizyt"
   },
   "worldtravel": {
     "country_list": "Lista krajów",

frontend/src/locales/sv.json

@@ -256,7 +256,8 @@
     "additional_info": "Ytterligare information",
     "invalid_date_range": "Ogiltigt datumintervall",
     "sunrise_sunset": "Soluppgång",
-    "timezone": "Tidszon"
+    "timezone": "Tidszon",
+    "no_visits": "Inga besök"
   },
   "home": {
     "desc_1": "Upptäck, planera och utforska med lätthet",

frontend/src/locales/zh.json

@@ -304,7 +304,8 @@
     "additional_info": "附加信息",
     "invalid_date_range": "无效的日期范围",
     "sunrise_sunset": "日出",
-    "timezone": "时区"
+    "timezone": "时区",
+    "no_visits": "没有访问"
   },
   "auth": {
     "forgot_password": "忘记密码？",