add initial project structure with configuration, models, and API key authentication

internal/models/session.go

@@ -0,0 +1,11 @@
+package models
+
+import "time"
+
+type Session struct {
+	ID        string    `db:"id"         json:"id"`
+	UserID    int64     `db:"user_id"    json:"user_id"`
+	Token     string    `db:"token"      json:"token"`
+	ExpiresAt time.Time `db:"expires_at" json:"expires_at"`
+	CreatedAt time.Time `db:"created_at" json:"created_at"`
+}