feature/gamification features

[codebude]

• Add dashboard gamification (reading streaks & goals)
• Refresh reading streak after logging progress
• Add option to disable gamification on dashboard
• Documentation of reading streaks and goals functionality
• Make hero card on dashboard smaller (reduce height)
• Reorder gamification card on dashboard
• Shuffle next-to-read suggestions on dashboard
• Update release notes for v1.7.0

[github-actions]

🧪 Test Results — df2273d

✅ Backend (pytest) — 960 passed, 0 failed, 0 skipped (960 total)
✅ CLI (pytest) — 54 passed, 0 failed, 0 skipped (54 total)
✅ Frontend (vitest) — 420 passed, 0 failed, 0 skipped (420 total)
✅ E2E (Playwright) — 75 passed, 0 failed, 0 skipped (75 total)

Summary: ✅ All 1509 tests passed