feat(logging): integrate slog logging with env control and request/sync tracing

- Configure structured slog logger in cmd/server/main.go via LOG_LEVEL and DEBUG env vars
- Add HTTP API request logging middleware in internal/api/ with status and duration_ms
- Add WebSocket join/leave, event reception, and debounced SQLite flush tracing in docroom
- Document LOG_LEVEL and DEBUG settings in .env.example, compose.yaml, and docker-compose.yml

cmd/server/main.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"embed"
 	"io/fs"
-	"log"
+	"log/slog"
 	"net/http"
 	"os"
 	"os/signal"
@@ -23,11 +23,16 @@ var embeddedDist embed.FS
 func main() {
 	cfg := config.Load()
 
-	log.Printf("🧠 Starting MindSift Server on port %s (DB: %s)", cfg.Port, cfg.DatabasePath)
+	level := cfg.SlogLevel()
+	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: level}))
+	slog.SetDefault(logger)
+
+	slog.Info("MindSift Server starting", "port", cfg.Port, "log_level", level.String())
 
 	store, err := storage.NewStore(cfg.DatabasePath)
 	if err != nil {
-		log.Fatalf("Failed to initialize storage: %v", err)
+		slog.Error("Failed to initialize storage", "error", err)
+		os.Exit(1)
 	}
 	defer store.Close()
 
@@ -35,11 +40,11 @@ func main() {
 	store.SeedSMTPDefaultsFromEnv(cfg.SMTPHost, cfg.SMTPPort, cfg.SMTPUser, cfg.SMTPPass, cfg.SMTPFrom, cfg.SMTPTLS)
 
 	if cfg.DemoMode {
-		log.Printf("🧪 Demo-Modus aktiv (MINDA_DEMO=true): Richte Demo-Benutzer admin/admin und user/user ein...")
+		slog.Info("🧪 Demo-Modus aktiv (MINDA_DEMO=true): Richte Demo-Benutzer admin/admin und user/user ein...")
 		if err := store.EnsureDemoAccounts(); err != nil {
-			log.Printf("⚠️ Fehler beim Anlegen der Demo-Accounts: %v", err)
+			slog.Warn("⚠️ Fehler beim Anlegen der Demo-Accounts", "error", err)
 		} else {
-			log.Printf("✅ Demo-Accounts bereit: admin / admin (Admin-Rolle) und user / user (Standard-Rolle)")
+			slog.Info("✅ Demo-Accounts bereit: admin / admin (Admin-Rolle) und user / user (Standard-Rolle)")
 		}
 	}
 
@@ -47,7 +52,8 @@ func main() {
 
 	staticFS, err := fs.Sub(embeddedDist, "dist")
 	if err != nil {
-		log.Fatalf("Failed to mount embedded dist filesystem: %v", err)
+		slog.Error("Failed to mount embedded dist filesystem", "error", err)
+		os.Exit(1)
 	}
 
 	srv := api.NewServer(cfg, store, wsHub, staticFS)
@@ -61,9 +67,10 @@ func main() {
 	}
 
 	go func() {
-		log.Printf("✨ MindSift ready at http://0.0.0.0:%s", cfg.Port)
+		slog.Info("✨ MindSift ready", "url", "http://0.0.0.0:"+cfg.Port)
 		if err := httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
-			log.Fatalf("HTTP server error: %v", err)
+			slog.Error("HTTP server error", "error", err)
+			os.Exit(1)
 		}
 	}()
 
@@ -71,7 +78,7 @@ func main() {
 	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
 	<-stop
 
-	log.Println("Shutting down MindSift server gracefully...")
+	slog.Info("Shutting down MindSift server gracefully...")
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 	_ = httpServer.Shutdown(ctx)