feat: implement label management with color filtering

keep-notes/lib/types.ts

@@ -4,6 +4,15 @@ export interface CheckItem {
   checked: boolean;
 }
 
+export interface Label {
+  id: string;
+  name: string;
+  color: LabelColorName;
+  userId?: string | null;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
 export interface Note {
   id: string;
   title: string | null;