refactor(entrypoint): propagate errors from route registration and stream serving

Changed AddRoute and ListenAndServe methods to return errors instead of logging them internally and continuing. This allows callers to properly handle and propagate errors, improving error visibility and enabling better error management across the codebase. Updated all callers in fileserver, reverse_proxy, stream routes to handle these errors appropriately.

internal/entrypoint/types/entrypoint.go

@@ -10,7 +10,7 @@ type Entrypoint interface {
 	DisablePoolsLog(v bool)
 
 	GetRoute(alias string) (types.Route, bool)
-	AddRoute(r types.Route)
+	AddRoute(r types.Route) error
 	IterRoutes(yield func(r types.Route) bool)
 	NumRoutes() int
 	RoutesByProvider() map[string][]types.Route