Initial commit: party-mix-app with prefetch cache, audio preload optimizations

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

apps/backend/internal/database/database.go

@@ -0,0 +1,39 @@
+package database
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/toyffee/party-mix/internal/config"
+	"github.com/toyffee/party-mix/internal/models"
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+func Connect(cfg *config.Config) *gorm.DB {
+	dsn := fmt.Sprintf(
+		"host=%s user=%s password=%s dbname=%s port=%s sslmode=disable TimeZone=UTC",
+		cfg.DBHost, cfg.DBUser, cfg.DBPass, cfg.DBName, cfg.DBPort,
+	)
+	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Warn),
+	})
+	if err != nil {
+		log.Fatalf("database connection failed: %v", err)
+	}
+	if err := db.AutoMigrate(
+		&models.Party{},
+		&models.Participant{},
+		&models.Track{},
+		&models.HistoryItem{},
+		&models.User{},
+		&models.Playlist{},
+		&models.PlaylistTrack{},
+		&models.UserVersion{},
+	); err != nil {
+		log.Fatalf("database migration failed: %v", err)
+	}
+	log.Println("Database connected and migrated")
+	return db
+}