Phase 1 of scanner restoration plan
Changes:
- cmd/server/main.go: Capture ebookHandler from router.RegisterRoutes
- cmd/server/main.go: Start scheduler in background goroutine
- cmd/server/main.go: Defer StopScheduler() for graceful shutdown
- cmd/server/main.go: Start watch mode for all libraries after 2-second delay
- internal/router/router.go: Return ebookHandler from RegisterRoutes
This restores critical functionality that was removed during router refactor:
- Auto-scanning now works again
- Watch mode starts automatically for all libraries
- Graceful shutdown properly stops scheduler
Fixes issue where scheduler and watch mode were not starting on server boot.