Implements strategy pattern for calendar views

Refactors the grid management to use a strategy pattern, allowing for different calendar views (week, month, day) to be rendered using separate strategy implementations.

This approach improves code organization, reduces complexity within the main grid manager, and makes it easier to add new view types in the future.

The strategy pattern centralizes view-specific logic, improves testability, and reduces code duplication.

A month view strategy has been added and is now selectable via UI.

src/strategies/MonthViewStrategy.ts

@@ -0,0 +1,148 @@
+/**
+ * MonthViewStrategy - Strategy for month view rendering
+ * Completely different from week view - no time axis, cell-based events
+ */
+
+import { ViewStrategy, ViewContext, ViewLayoutConfig } from './ViewStrategy';
+import { DateCalculator } from '../utils/DateCalculator';
+import { calendarConfig } from '../core/CalendarConfig';
+
+export class MonthViewStrategy implements ViewStrategy {
+  private dateCalculator: DateCalculator;
+  
+  constructor() {
+    this.dateCalculator = new DateCalculator(calendarConfig);
+  }
+  
+  getLayoutConfig(): ViewLayoutConfig {
+    return {
+      needsTimeAxis: false,        // No time axis in month view!
+      columnCount: 7,              // Always 7 days (Mon-Sun)
+      scrollable: false,           // Month fits in viewport
+      eventPositioning: 'cell-based'  // Events go in day cells
+    };
+  }
+  
+  renderGrid(context: ViewContext): void {
+    console.group(`📅 MONTH VIEW: Rendering grid for ${context.currentDate.toDateString()}`);
+    
+    // Clear existing content
+    context.container.innerHTML = '';
+    
+    // Create month grid (completely different from week!)
+    this.createMonthGrid(context);
+    
+    console.log('Month grid rendered with 7x6 layout');
+    console.groupEnd();
+  }
+  
+  private createMonthGrid(context: ViewContext): void {
+    const monthGrid = document.createElement('div');
+    monthGrid.className = 'month-grid';
+    monthGrid.style.display = 'grid';
+    monthGrid.style.gridTemplateColumns = 'repeat(7, 1fr)';
+    monthGrid.style.gridTemplateRows = 'auto repeat(6, 1fr)';
+    monthGrid.style.height = '100%';
+    
+    // Add day headers (Mon, Tue, Wed, etc.)
+    this.createDayHeaders(monthGrid);
+    
+    // Add 6 weeks of day cells
+    this.createDayCells(monthGrid, context.currentDate);
+    
+    // Render events in day cells
+    this.renderMonthEvents(monthGrid, context.allDayEvents);
+    
+    context.container.appendChild(monthGrid);
+  }
+  
+  private createDayHeaders(container: HTMLElement): void {
+    const dayNames = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'];
+    
+    dayNames.forEach(dayName => {
+      const header = document.createElement('div');
+      header.className = 'month-day-header';
+      header.textContent = dayName;
+      header.style.padding = '8px';
+      header.style.fontWeight = 'bold';
+      header.style.textAlign = 'center';
+      header.style.borderBottom = '1px solid #e0e0e0';
+      container.appendChild(header);
+    });
+  }
+  
+  private createDayCells(container: HTMLElement, monthDate: Date): void {
+    const dates = this.getMonthDates(monthDate);
+    
+    dates.forEach(date => {
+      const cell = document.createElement('div');
+      cell.className = 'month-day-cell';
+      cell.dataset.date = this.dateCalculator.formatISODate(date);
+      cell.style.border = '1px solid #e0e0e0';
+      cell.style.minHeight = '100px';
+      cell.style.padding = '4px';
+      cell.style.position = 'relative';
+      
+      // Day number
+      const dayNumber = document.createElement('div');
+      dayNumber.className = 'month-day-number';
+      dayNumber.textContent = date.getDate().toString();
+      dayNumber.style.fontWeight = 'bold';
+      dayNumber.style.marginBottom = '4px';
+      
+      // Check if today
+      if (this.dateCalculator.isToday(date)) {
+        dayNumber.style.color = '#1976d2';
+        cell.style.backgroundColor = '#f5f5f5';
+      }
+      
+      cell.appendChild(dayNumber);
+      container.appendChild(cell);
+    });
+  }
+  
+  private getMonthDates(monthDate: Date): Date[] {
+    // Get first day of month
+    const firstOfMonth = new Date(monthDate.getFullYear(), monthDate.getMonth(), 1);
+    
+    // Get Monday of the week containing first day
+    const startDate = this.dateCalculator.getISOWeekStart(firstOfMonth);
+    
+    // Generate 42 days (6 weeks)
+    const dates: Date[] = [];
+    for (let i = 0; i < 42; i++) {
+      dates.push(this.dateCalculator.addDays(startDate, i));
+    }
+    
+    return dates;
+  }
+  
+  private renderMonthEvents(container: HTMLElement, events: any[]): void {
+    // TODO: Implement month event rendering
+    // Events will be small blocks in day cells
+    console.log(`MonthViewStrategy: Would render ${events.length} events`);
+  }
+  
+  getNextPeriod(currentDate: Date): Date {
+    return new Date(currentDate.getFullYear(), currentDate.getMonth() + 1, 1);
+  }
+  
+  getPreviousPeriod(currentDate: Date): Date {
+    return new Date(currentDate.getFullYear(), currentDate.getMonth() - 1, 1);
+  }
+  
+  getPeriodLabel(date: Date): string {
+    const monthNames = ['January', 'February', 'March', 'April', 'May', 'June',
+                       'July', 'August', 'September', 'October', 'November', 'December'];
+    
+    return `${monthNames[date.getMonth()]} ${date.getFullYear()}`;
+  }
+  
+  getDisplayDates(baseDate: Date): Date[] {
+    return this.getMonthDates(baseDate);
+  }
+  
+  destroy(): void {
+    console.log('MonthViewStrategy: Cleaning up');
+  }
+}