Add learning progress components (ProgressTracker, LessonCard, QuizBlock)

[PetarStoev02]

Description

UI components for the educational/LMS features of w3-kit.

Scope

• ProgressTracker — visual progress bar for course/section completion
• LessonCard — card showing lesson title, difficulty, estimated time, completion status
• QuizBlock — inline quiz component with multiple choice, code completion challenges
• CertificateBadge — display on-chain completion certificates

All should follow the existing shadcn registry pattern.