refactor(config): simplify route provider loading with improved error handling

Streamlined the `loadRouteProviders()` function by:
- Replacing channel-based concurrency with a simpler sequential registration pattern after agent initialization
- Using `gperr.NewGroup` and `gperr.NewBuilder` for more idiomatic error handling
- Adding mutex protection for concurrent result building
- Removing the `storeProvider` helper method

internal/config/state.go

@@ -317,67 +317,50 @@ func (state *state) initProxmox() error {
 	return errs.Wait().Error()
 }
 
-func (state *state) storeProvider(p types.RouteProvider) {
-	state.providers.Store(p.String(), p)
-}
-
 func (state *state) loadRouteProviders() error {
-	providers := &state.Providers
+	providers := state.Providers
 	errs := gperr.NewGroup("route provider errors")
-	results := gperr.NewGroup("loaded route providers")
 
 	agentpool.RemoveAll()
 
-	numProviders := len(providers.Agents) + len(providers.Files) + len(providers.Docker)
-	providersCh := make(chan types.RouteProvider, numProviders)
-
-	// start providers concurrently
-	var providersConsumer sync.WaitGroup
-	providersConsumer.Go(func() {
-		for p := range providersCh {
-			if actual, loaded := state.providers.LoadOrStore(p.String(), p); loaded {
-				errs.Add(gperr.Errorf("provider %s already exists, first: %s, second: %s", p.String(), actual.GetType(), p.GetType()))
-				continue
-			}
-			state.storeProvider(p)
+	registerProvider := func(p types.RouteProvider) {
+		if actual, loaded := state.providers.LoadOrStore(p.String(), p); loaded {
+			errs.Addf("provider %s already exists, first: %s, second: %s", p.String(), actual.GetType(), p.GetType())
 		}
-	})
+	}
 
-	var providersProducer sync.WaitGroup
+	agentErrs := gperr.NewGroup("agent init errors")
 	for _, a := range providers.Agents {
-		providersProducer.Go(func() {
+		agentErrs.Go(func() error {
 			if err := a.Init(state.task.Context()); err != nil {
-				errs.Add(gperr.PrependSubject(a.String(), err))
-				return
+				return gperr.PrependSubject(a.String(), err)
 			}
 			agentpool.Add(a)
-			p := route.NewAgentProvider(a)
-			providersCh <- p
+			return nil
 		})
 	}
 
+	if err := agentErrs.Wait().Error(); err != nil {
+		errs.Add(err)
+	}
+
+	for _, a := range providers.Agents {
+		registerProvider(route.NewAgentProvider(a))
+	}
+
 	for _, filename := range providers.Files {
-		providersProducer.Go(func() {
-			p, err := route.NewFileProvider(filename)
-			if err != nil {
-				errs.Add(gperr.PrependSubject(filename, err))
-			} else {
-				providersCh <- p
-			}
-		})
+		p, err := route.NewFileProvider(filename)
+		if err != nil {
+			errs.Add(gperr.PrependSubject(filename, err))
+			return err
+		}
+		registerProvider(p)
 	}
 
 	for name, dockerCfg := range providers.Docker {
-		providersProducer.Go(func() {
-			providersCh <- route.NewDockerProvider(name, dockerCfg)
-		})
+		registerProvider(route.NewDockerProvider(name, dockerCfg))
 	}
 
-	providersProducer.Wait()
-
-	close(providersCh)
-	providersConsumer.Wait()
-
 	lenLongestName := 0
 	for k := range state.providers.Range {
 		if len(k) > lenLongestName {
@@ -386,18 +369,26 @@ func (state *state) loadRouteProviders() error {
 	}
 
 	// load routes concurrently
-	var providersLoader sync.WaitGroup
+	loadErrs := gperr.NewGroup("route load errors")
+
+	results := gperr.NewBuilder("loaded route providers")
+	resultsMu := sync.Mutex{}
 	for _, p := range state.providers.Range {
-		providersLoader.Go(func() {
+		loadErrs.Go(func() error {
 			if err := p.LoadRoutes(); err != nil {
-				errs.Add(err.Subject(p.String()))
+				return err.Subject(p.String())
 			}
+			resultsMu.Lock()
 			results.Addf("%-"+strconv.Itoa(lenLongestName)+"s %d routes", p.String(), p.NumRoutes())
+			resultsMu.Unlock()
+			return nil
 		})
 	}
-	providersLoader.Wait()
+	if err := loadErrs.Wait().Error(); err != nil {
+		errs.Add(err)
+	}
 
-	state.tmpLog.Info().Msg(results.Wait().String())
+	state.tmpLog.Info().Msg(results.String())
 	state.printRoutesByProvider(lenLongestName)
 	state.printState()
 	return errs.Wait().Error()