feat: added session guid and token type fields to jwt tokens;

feat: very minimal implementation of registration functions;
refactor: login function now uses the transactional db helper function and creates a session;
feat: enum for jwt token type

backend/internal/middleware/auth.go

@@ -34,6 +34,8 @@ type Claims struct {
 	jwt.RegisteredClaims
 }
 
+// TODO: validate token type
+// TODO: validate session guid
 func AuthMiddleware() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		cfg := config.GetConfig()