feat(PROJ-17): Admin Dashboard Systemauslastung immer anzeigen

- Systemauslastungs-Sektion wird immer gerendert (nicht nur bei Erfolg)
- Fehlermeldung wenn /api/admin/system/stats nicht erreichbar ist
- Feature-Status auf In Review gesetzt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cmd/archivmail-export/main.go

@@ -0,0 +1,117 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log/slog"
+	"os"
+	"path/filepath"
+
+	"github.com/archivmail/config"
+	"github.com/archivmail/internal/index"
+	"github.com/archivmail/internal/storage"
+)
+
+func main() {
+	configPath := flag.String("config", "/etc/archivmail/config.yml", "path to config file")
+	format := flag.String("format", "eml", "export format: eml or pdf")
+	outDir := flag.String("out", "./export", "output directory")
+	flag.Parse()
+
+	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelInfo}))
+
+	if *format == "pdf" {
+		fmt.Fprintln(os.Stdout, "PDF export not yet implemented")
+		os.Exit(0)
+	}
+
+	if *format != "eml" {
+		fmt.Fprintf(os.Stderr, "unknown format: %s (supported: eml, pdf)\n", *format)
+		os.Exit(1)
+	}
+
+	cfg, err := config.Load(*configPath)
+	if err != nil {
+		logger.Error("failed to load config", "err", err)
+		os.Exit(1)
+	}
+
+	mailStore, err := storage.New(cfg.Storage.StorePath)
+	if err != nil {
+		logger.Error("storage init failed", "err", err)
+		os.Exit(1)
+	}
+
+	indexBackend := cfg.Index.Backend
+	if indexBackend == "" {
+		indexBackend = "xapian"
+	}
+	batchSize := cfg.Index.BatchSize
+	if batchSize <= 0 {
+		batchSize = 100
+	}
+	idx, err := index.New(cfg.Index.Path, batchSize, indexBackend)
+	if err != nil {
+		logger.Error("index init failed", "err", err)
+		os.Exit(1)
+	}
+	defer idx.Close()
+
+	if err := os.MkdirAll(*outDir, 0o755); err != nil {
+		logger.Error("cannot create output directory", "dir", *outDir, "err", err)
+		os.Exit(1)
+	}
+
+	// Fetch all indexed mails using pagination
+	page := 0
+	pageSize := 500
+	exported := 0
+	errors := 0
+
+	for {
+		result, err := idx.Search(index.SearchRequest{
+			PageSize: pageSize,
+			Page:     page,
+		})
+		if err != nil {
+			logger.Error("search failed", "err", err)
+			os.Exit(1)
+		}
+
+		if len(result.Hits) == 0 {
+			break
+		}
+
+		for _, hit := range result.Hits {
+			raw, err := mailStore.Load(hit.ID)
+			if err != nil {
+				logger.Error("load failed", "id", hit.ID, "err", err)
+				errors++
+				continue
+			}
+
+			outPath := filepath.Join(*outDir, hit.ID+".eml")
+			if err := os.WriteFile(outPath, raw, 0o644); err != nil {
+				logger.Error("write failed", "path", outPath, "err", err)
+				errors++
+				continue
+			}
+
+			exported++
+		}
+
+		logger.Info("export progress", "page", page, "exported", exported, "errors", errors)
+
+		if exported+errors >= result.Total {
+			break
+		}
+		page++
+	}
+
+	logger.Info("export complete",
+		"format", *format,
+		"out", *outDir,
+		"exported", exported,
+		"errors", errors,
+	)
+}