Add initial project structure with database connection and routing setup

- Create .env.example and .gitignore to manage environment variables
- Implement database connection logic in bd.go
- Define project model and data retrieval functions in projet.go
- Set up HTTP routes for project management in routes/projet.go
- Add main entry point in main.go to start the server

bd/bd.go

@@ -0,0 +1,38 @@
+package bd
+
+import (
+	"database/sql"
+	"log"
+	"os"
+
+	"github.com/go-sql-driver/mysql"
+	"github.com/joho/godotenv"
+)
+
+var db *sql.DB
+
+func GetDB() *sql.DB {
+
+	if db == nil {
+		errenv := godotenv.Load()
+		if errenv != nil {
+			log.Fatal("Error loading .env file")
+		}
+		// Capture connection properties.
+		cfg := mysql.NewConfig()
+		cfg.User = os.Getenv("DB_USER")
+		cfg.Passwd = os.Getenv("DB_PASS")
+		cfg.Net = "tcp"
+		cfg.Addr = os.Getenv("DB_HOST")
+		cfg.DBName = os.Getenv("DB_NAME")
+
+		// Get a database handle.
+		var err error
+		db, err = sql.Open("mysql", cfg.FormatDSN())
+		if err != nil {
+			log.Fatal(err)
+		}
+
+	}
+	return db
+}