feat: add database configuration for PostgreSQL

- Create config/database.go with GORM PostgreSQL connection
- Support environment-based database configuration
- Add connection logging and error handling

config/database.go

@@ -0,0 +1,28 @@
+package config
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+)
+
+func InitDB() *gorm.DB {
+	host := os.Getenv("PG_HOST")
+	port := os.Getenv("PG_PORT")
+	database := os.Getenv("PG_DATABASE")
+	user := os.Getenv("PG_USER")
+	password := os.Getenv("PG_PASSWORD")
+
+	// Try with quoted password
+	dsn := fmt.Sprintf(`host=%s port=%s user=%s password='%s' dbname=%s sslmode=disable`,
+		host, port, user, password, database)
+
+	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
+	if err != nil {
+		log.Fatal("Failed to connect to database:", err)
+	}
+	return db
+}