Add language assistant features and improve encryption handling: Implement a new route and controller method for sending messages to the language assistant, enhancing user interaction within lessons. Update the encryption utility to support both base64 and hex formats for better compatibility with existing data. Enhance localization files to include new terms related to the language assistant in English, German, and Spanish, improving user experience across languages.

frontend/src/i18n/locales/en/socialnetwork.json

@@ -438,7 +438,34 @@
                 "recognizedText": "Recognized Text",
                 "speechRecognitionNotSupported": "Speech Recognition is not supported by this browser. Please use Chrome or Edge.",
                 "keywords": "Keywords",
-                "switchBackToMultipleChoice": "Switch back to Multiple Choice"
+                "switchBackToMultipleChoice": "Switch back to Multiple Choice",
+                "languageAssistantEyebrow": "Language assistant",
+                "languageAssistantCourseTitle": "AI support for this course",
+                "languageAssistantCourseReady": "The language assistant is configured and available inside lessons for explanations, corrections, and short dialogue practice.",
+                "languageAssistantCourseSetup": "Set up the language assistant so you can ask lesson-specific questions and practice short dialogues.",
+                "languageAssistantOpenLesson": "Open in current lesson",
+                "languageAssistantTitle": "Practice with the language assistant",
+                "languageAssistantIntro": "Use the AI directly inside the current lesson: get grammar explained, practice short dialogues, or have your own sentences corrected.",
+                "languageAssistantSettings": "Configure assistant",
+                "languageAssistantSetupHint": "The language assistant is not configured yet or is currently disabled. Please save your model and API access in the settings first.",
+                "languageAssistantModePractice": "Practice",
+                "languageAssistantModeExplain": "Explain",
+                "languageAssistantModeCorrect": "Correct",
+                "languageAssistantPromptExplain": "Explain grammar",
+                "languageAssistantPromptPractice": "Practice mini dialogue",
+                "languageAssistantPromptCorrect": "Improve my sentence",
+                "languageAssistantSpeakerAi": "Language assistant",
+                "languageAssistantSpeakerYou": "You",
+                "languageAssistantInputLabel": "Your message",
+                "languageAssistantInputPlaceholder": "Ask a lesson question or write your own sentence for correction.",
+                "languageAssistantSend": "Send to assistant",
+                "languageAssistantSending": "Getting answer ...",
+                "languageAssistantError": "The language assistant could not answer right now.",
+                "languageAssistantPresetExplainStart": "Please explain the main patterns and grammar in the lesson",
+                "languageAssistantPatternHint": "Focus especially on this pattern",
+                "languageAssistantPresetPracticeStart": "Let's practice a short everyday dialogue for the lesson \"{lesson}\". Please ask me questions and wait for my answers.",
+                "languageAssistantPresetCorrectStart": "I want to write my own sentences for the lesson \"{lesson}\". Please correct my answers briefly and clearly.",
+                "thisLesson": "this lesson"
             }
         }
     }