feat: add independent platform modules and multi-provider storage

auth/auth.go

@@ -21,9 +21,10 @@ var (
 // Principal is the authenticated identity made available to business handlers.
 // Claims are optional provider-specific values and should not be required by core business code.
 type Principal struct {
-	UserID string
-	Roles  []string
-	Claims map[string]any
+	UserID   string         `json:"userId"`
+	TenantID string         `json:"tenantId,omitempty"`
+	Roles    []string       `json:"roles,omitempty"`
+	Claims   map[string]any `json:"claims,omitempty"`
 }
 
 func (p Principal) HasRole(role string) bool {