feat(m3u): add group management translations and hints for channels

apps/web/src/assets/i18n/de.json

@@ -5,7 +5,10 @@
         "ALL_CHANNELS": "Alle Sender",
         "FAVORITES": "Favoriten",
         "GROUPS": "Gruppen",
+        "MANAGE_GROUPS": "Gruppen verwalten",
+        "MANAGE_GROUPS_HINT": "Verwenden Sie \"Gruppen verwalten\", um Gruppen wieder einzublenden.",
         "NO_FAVORITES": "Keine Favoriten",
+        "NO_VISIBLE_GROUPS": "Keine sichtbaren Gruppen",
         "REMOVE_FAVORITE": "Aus Favoritenliste entfernen",
         "SEARCH_CHANNEL": "Nach Sender suchen",
         "UNGROUPED": "Ohne Gruppe",
@@ -17,7 +20,16 @@
         "SORT_BY": "Sortieren nach",
         "SORT_BY_DATE": "Nach Datum sortieren (Neueste zuerst)",
         "SORT_BY_RATING": "Nach Bewertung sortieren",
-        "SORT_BY_NAME": "Nach Name sortieren (A-Z)"
+        "SORT_BY_NAME": "Nach Name sortieren (A-Z)",
+        "GROUP_MANAGEMENT": {
+            "TITLE": "Gruppen verwalten",
+            "SELECTED": "Ausgewählt",
+            "SELECT_ALL": "Alle auswählen",
+            "DESELECT_ALL": "Alle abwählen",
+            "SEARCH_PLACEHOLDER": "Gruppen suchen...",
+            "NO_RESULTS": "Keine passenden Gruppen gefunden",
+            "SAVE": "Speichern"
+        }
     },
     "EPG": {
         "TITLE": "Elektronischer Programmführer",

apps/web/src/assets/i18n/en.json

@@ -272,6 +272,9 @@
         "UPLOAD_OR_SELECT_OTHER_PLAYLIST": "Upload or select other playlist",
         "ALL_CHANNELS": "All channels",
         "GROUPS": "Groups",
+        "MANAGE_GROUPS": "Manage groups",
+        "MANAGE_GROUPS_HINT": "Use manage groups to show groups again.",
+        "NO_VISIBLE_GROUPS": "No visible groups",
         "UNGROUPED": "Ungrouped",
         "UNNAMED_CHANNEL": "Unnamed Channel",
         "FAVORITES": "Favorites",
@@ -325,6 +328,15 @@
             "NOT_AVAILABLE": "Not available",
             "DAYS_ONE": "1 day",
             "DAYS_OTHER": "{{count}} days"
+        },
+        "GROUP_MANAGEMENT": {
+            "TITLE": "Manage groups",
+            "SELECTED": "Selected",
+            "SELECT_ALL": "Select all",
+            "DESELECT_ALL": "Deselect all",
+            "SEARCH_PLACEHOLDER": "Search groups...",
+            "NO_RESULTS": "No matching groups found",
+            "SAVE": "Save"
         }
     },
     "TOP_MENU": {