feat(dashboard): add content page options menu (#757)

* feat(dashboard): add content page options menu

Add a three-dot menu on the course Content page with actions to unlock
all locked lessons/exercises and toggle content grouping. Reuse shared
locked-content collection logic from course settings.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): keep unlock-all enabled and add menu icons

Show a success snackbar when all content is already unlocked instead of
disabling the action. Add lock-open and table-of-contents icons to menu items.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix(dashboard): check courseApi.update return for grouping toggle

Use the update() return value instead of courseApi.success, which can be
false after a successful PUT if the follow-up refresh request fails.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

---------

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

apps/dashboard/src/lib/utils/translations/de.json

@@ -289,7 +289,10 @@
         "successful_integration": "Integration erfolgreich",
         "successful_deletion": "Integration gelöscht",
         "update_successful": "Update erfolgreich",
-        "unlocked_all_content": "Alle Kursgegenstände freigeschaltet"
+        "unlocked_all_content": "Alle Kursgegenstände freigeschaltet",
+        "all_content_already_unlocked": "Alle Inhalte sind bereits freigeschaltet",
+        "content_grouping_enabled": "Inhaltsgruppierung aktiviert",
+        "content_grouping_disabled": "Inhaltsgruppierung deaktiviert"
       }
     },
     "people": {
@@ -1320,6 +1323,12 @@
         "add_content_create_lesson": "Lektion erstellen",
         "add_content_section_title_placeholder": "z. B. Modul 1: Einführung",
         "add_content_lesson_title_placeholder": "z. B. Erste Schritte mit Variablen",
+        "content_menu": {
+          "label": "Inhaltsoptionen",
+          "unlock_all": "Alle Inhalte freischalten",
+          "enable_grouping": "Inhaltsgruppierung aktivieren",
+          "disable_grouping": "Inhaltsgruppierung deaktivieren"
+        },
         "join_lesson": "Nehmen Sie an der Lektion teil",
         "no_link": "Kein Link",
         "no_tutor": "Kein Tutor hinzugefügt",