feat: add configurable timeline range

src/types.ts

@@ -63,6 +63,7 @@ export interface Connection {
 }
 
 export interface Viewport { x: number; y: number; zoom: number }
+export interface TimelineRange { start: string; end: string }
 
 export interface BriefConcept {
   id: string
@@ -83,6 +84,7 @@ export interface CaseState {
   relations: WidgetRelation[]
   connections: Connection[]
   viewport: Viewport
+  timelineRange?: TimelineRange | null
   brief: LevelBrief
   updatedAt?: string
   levelStatus?: string