Refactor calendar navigation with flexible day offsets

Improves date navigation by introducing dynamic period-based offsets for calendar views

Replaces week-based navigation with more flexible day offsets that support:
- Single-day and multi-day navigation
- Configurable work week presets with different period lengths
- More granular control over date range selection

Adds support for dynamic navigation periods through workweek preset configuration

src/core/CalendarApp.ts

@@ -24,7 +24,7 @@ import {
 export class CalendarApp {
   private animator!: NavigationAnimator;
   private container!: HTMLElement;
-  private weekOffset = 0;
+  private dayOffset = 0;
   private currentViewId = 'simple';
   private workweekPreset: IWorkweekPreset | null = null;
   private groupingOverrides: Map<string, string[]> = new Map();
@@ -126,13 +126,15 @@ export class CalendarApp {
   }
 
   private async handleNavigatePrev(): Promise<void> {
-    this.weekOffset--;
+    const step = this.workweekPreset?.periodDays ?? 7;
+    this.dayOffset -= step;
     await this.animator.slide('right', () => this.render());
     this.emitStatus('rendered', { viewId: this.currentViewId });
   }
 
   private async handleNavigateNext(): Promise<void> {
-    this.weekOffset++;
+    const step = this.workweekPreset?.periodDays ?? 7;
+    this.dayOffset += step;
     await this.animator.slide('left', () => this.render());
     this.emitStatus('rendered', { viewId: this.currentViewId });
   }
@@ -159,11 +161,15 @@ export class CalendarApp {
       return;
     }
 
-    // Populate date values based on workweek and offset
+    // Populate date values based on workweek preset and day offset
     const workDays = this.workweekPreset?.workDays || [1, 2, 3, 4, 5];
-    const dates = this.currentViewId === 'day'
-      ? this.dateService.getWeekDates(this.weekOffset, 1)
-      : this.dateService.getWorkWeekDates(this.weekOffset, workDays);
+    const periodDays = this.workweekPreset?.periodDays ?? 7;
+
+    // For single-day navigation (periodDays=1), show consecutive days from offset
+    // For week navigation (periodDays=7), show workDays from the week containing offset
+    const dates = periodDays === 1
+      ? this.dateService.getDatesFromOffset(this.dayOffset, workDays.length)
+      : this.dateService.getWorkDaysFromOffset(this.dayOffset, workDays);
 
     // Clone config and apply overrides
     const viewConfig: ViewConfig = {

src/core/DateService.ts

@@ -41,21 +41,30 @@ export class DateService {
     return new Intl.DateTimeFormat(this.config.locale, { weekday: format }).format(date);
   }
 
-  getWeekDates(offset = 0, days = 7): string[] {
-    const monday = this.baseDate.startOf('week').add(1, 'day').add(offset, 'week');
-    return Array.from({ length: days }, (_, i) =>
-      monday.add(i, 'day').format('YYYY-MM-DD')
+  /**
+   * Get dates starting from a day offset
+   * @param dayOffset - Day offset from base date
+   * @param count - Number of consecutive days to return
+   * @returns Array of date strings in YYYY-MM-DD format
+   */
+  getDatesFromOffset(dayOffset: number, count: number): string[] {
+    const startDate = this.baseDate.add(dayOffset, 'day');
+    return Array.from({ length: count }, (_, i) =>
+      startDate.add(i, 'day').format('YYYY-MM-DD')
     );
   }
 
   /**
-   * Get dates for specific weekdays within a week
-   * @param offset - Week offset from base date (0 = current week)
+   * Get specific weekdays from the week containing the offset date
+   * @param dayOffset - Day offset from base date
    * @param workDays - Array of ISO weekday numbers (1=Monday, 7=Sunday)
    * @returns Array of date strings in YYYY-MM-DD format
    */
-  getWorkWeekDates(offset: number, workDays: number[]): string[] {
-    const monday = this.baseDate.startOf('week').add(1, 'day').add(offset, 'week');
+  getWorkDaysFromOffset(dayOffset: number, workDays: number[]): string[] {
+    // Get the date at offset, then find its week's Monday
+    const targetDate = this.baseDate.add(dayOffset, 'day');
+    const monday = targetDate.startOf('week').add(1, 'day');
+
     return workDays.map(isoDay => {
       // ISO: 1=Monday, 7=Sunday → days from Monday: 0-6
       const daysFromMonday = isoDay === 7 ? 6 : isoDay - 1;
@@ -63,6 +72,15 @@ export class DateService {
     });
   }
 
+  // Legacy methods for backwards compatibility
+  getWeekDates(weekOffset = 0, days = 7): string[] {
+    return this.getDatesFromOffset(weekOffset * 7, days);
+  }
+
+  getWorkWeekDates(weekOffset: number, workDays: number[]): string[] {
+    return this.getWorkDaysFromOffset(weekOffset * 7, workDays);
+  }
+
   // ============================================
   // FORMATTING
   // ============================================

src/types/SettingsTypes.ts

@@ -17,6 +17,7 @@ export interface IWorkweekPreset {
   id: string;
   workDays: number[];
   label: string;
+  periodDays: number;  // Navigation step in days (1 = day, 7 = week)
 }
 
 /**