feat(i18n, vocab): enhance localization and vocabulary preparation in VocabLessonView

- Added new localization keys in German, English, and Spanish for exercise flow, progress, and learning path instructions, improving user guidance across languages.
- Updated VocabLessonView to incorporate these new keys, enhancing the clarity of vocabulary preparation steps and overall user experience during lessons.
- Refactored the layout to better present the learning path and vocabulary preparation stages, ensuring a more cohesive and informative interface.

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

@@ -431,6 +431,19 @@
                 "invalidCode": "Invalid code",
                 "courseNotFound": "Course not found",
                 "grammarExercises": "Chapter Test",
+                "exerciseFlowIntro": "Work through the tasks in order. Every correct answer moves you closer to completing the lesson.",
+                "exerciseProgressLabel": "Progress",
+                "exerciseTargetLabel": "Required",
+                "exerciseCardLabel": "Task {number}",
+                "exerciseStatusOpen": "Open",
+                "exerciseStatusCorrect": "Done",
+                "exerciseStatusRetry": "Try again",
+                "exerciseAnswerAllHint": "Answer all {total} tasks first. Completed so far: {answered}. You need at least {target}% to pass.",
+                "exerciseNeedMoreCorrectHint": "You currently have {score}%. You need at least {target}% to complete this lesson.",
+                "exercisePassedHint": "Target reached: {score}% out of the required {target}%. Once all tasks have been answered, the chapter test is passed.",
+                "exerciseReinforcementHint": "After a mistake, the flow returns briefly to learning mode. Practice {count} more trainer questions and the chapter test will unlock again.",
+                "exercisePrepReinforcementHint": "After a mistake, go through the prepared terms once more. Then the chapter test will unlock again.",
+                "exerciseGrammarLead": "Key grammar for this test",
                 "noExercises": "No test available",
                 "enterAnswer": "Enter answer",
                 "checkAnswer": "Check Answer",
@@ -456,6 +469,9 @@
                 "vocabPrepStep2": "Go through the same items again (active review, not testing yet).",
                 "vocabPrepConfirm2": "Second pass done",
                 "vocabPrepReady": "You can start the vocabulary trainer now.",
+                "learningPathLabel": "Main path",
+                "learningPathTitle": "Your learning flow for this lesson",
+                "learningPathIntro": "Work through these steps in order: prepare, review briefly, train, then move to the chapter test.",
                 "lessonDetailsToggle": "Show more lesson details",
                 "deepenSectionTitle": "Deepen and review",
                 "assistantSectionTitle": "Deepen with language assistant",