fix: align learn schema with existing LearnCourse/LearnModule models

- Remove duplicate Course/Module models (GitHub main already has LearnCourse/LearnModule)
- Add seed-learn.json with Daily Fiqh for Beginners (5 modules)
- Add seed-learn.js using prisma.learnCourse / prisma.learnModule
- Seed includes quizData, keyTakeaway, duration, giteaPath
- Matches existing API routes: /api/learn/courses, /api/learn/tts, /api/learn/progress

TODO:
- Add markdown content to modules (currently content field is null)
- Generate TTS audio files for listen toggle
- Add intermediate/advanced courses

prisma/schema.prisma

@@ -489,3 +489,4 @@ model LearnCertificate {
 // Add relations to User model
 /// NOTE: The Notification and Referral relations are declared on the models above.
 /// User now implicitly has: notifications Notification[], referredReferrals Referral[] (via "Referrer"), referrerReferral Referral? (via "Referred")
+