Restore complete Ent schema files

The schemas were incomplete (empty stubs). Restored complete schemas
from git history including refresh_token and user_role schemas, and
proper field definitions for auditlog and user entities.

ent/schema/role.go

@@ -1,6 +1,12 @@
 package schema
 
-import "entgo.io/ent"
+import (
+	"time"
+
+	"entgo.io/ent"
+	"entgo.io/ent/schema/edge"
+	"entgo.io/ent/schema/field"
+)
 
 // Role holds the schema definition for the Role entity.
 type Role struct {
@@ -9,10 +15,25 @@ type Role struct {
 
 // Fields of the Role.
 func (Role) Fields() []ent.Field {
-	return nil
+	return []ent.Field{
+		field.String("id").
+			Unique().
+			Immutable(),
+		field.String("name").
+			Unique().
+			NotEmpty(),
+		field.String("description").
+			Optional(),
+		field.Time("created_at").
+			Default(time.Now).
+			Immutable(),
+	}
 }
 
 // Edges of the Role.
 func (Role) Edges() []ent.Edge {
-	return nil
+	return []ent.Edge{
+		edge.To("role_permissions", RolePermission.Type),
+		edge.To("user_roles", UserRole.Type),
+	}
 }