refactor(router): update router comments and variable names

- Update comment: 'ebook handler' -> 'scanner handler'
- Rename ebookHandler variable to scannerHandler in router.go
- Update registerProgressRoutes parameter name
- Update registerScannerRoutes calls to use new variable name

internal/router/progress.go

@@ -4,7 +4,7 @@ import (
 	"bookhoard/internal/handlers"
 )
 
-func registerProgressRoutes(cfg *Config, ebookHandler *handlers.Handler) {
+func registerProgressRoutes(cfg *Config, scannerHandler *handlers.Handler) {
 	e := cfg.Echo
 
 	// JWT middleware for protected routes
@@ -12,7 +12,7 @@ func registerProgressRoutes(cfg *Config, ebookHandler *handlers.Handler) {
 	protected := e.Group("/api", jwtMiddleware)
 
 	// Universal Progress routes (Phase 1)
-	protected.GET("/progress/:id", ebookHandler.GetUniversalProgress)
-	protected.POST("/progress/:id", ebookHandler.UpdateUniversalProgress)
-	protected.GET("/progress/:id/history", ebookHandler.GetProgressHistory)
+	protected.GET("/progress/:id", scannerHandler.GetUniversalProgress)
+	protected.POST("/progress/:id", scannerHandler.UpdateUniversalProgress)
+	protected.GET("/progress/:id/history", scannerHandler.GetProgressHistory)
 }