feat: implement tweaks context for user preferences and remove TweaksPanel component

frontend/src/i18n/en.json

@@ -175,7 +175,15 @@
     "passwordsDoNotMatch": "Passwords do not match",
     "language": "Language",
     "languageLabel": "Language",
-    "languageDesc": "Select your preferred display language"
+    "languageDesc": "Select your preferred display language",
+    "appearance": "Appearance",
+    "themeLabel": "Theme",
+    "themeDesc": "Choose between light and dark mode",
+    "textSizeLabel": "Text size",
+    "textSizeDesc": "Adjust the base font size for readability",
+    "defaultFeedback": "Default Feedback",
+    "defaultFeedbackLabel": "Feedback mode",
+    "defaultFeedbackDesc": "Choose when to see answer feedback during exams"
   },
   "admin": {
     "administration": "Administration",