feat(careermap): fix chapter unlock, button responsiveness & completion flow with progress

[Ama-Dombawela]

• Fixed chapter unlock flow by saving pass status correctly and preventing retries from overwriting DB progress.
• Added Enter key support for both MCQ and fill-in-the-blank questions.
• Improved completion banners in the chapter selection page.
• Replaced all localStorage-based career progress tracking with DB-driven progress across CareerQuizPage, ResultsPage, and CareerChapterSelectionPage, ensuring progress persists across devices and browser clears.
• Simplified rewards to +10 XP per first pass, +5 XP on retry, and +1 token on full career completion