Adds navigation buttons management and refactors navigation

Introduces NavigationButtonsManager to handle navigation button interactions
Renames NavigationRenderer to WeekInfoRenderer for clarity
Adds new NAV_BUTTON_CLICKED event for better separation of concerns

Improves event-driven navigation workflow

src/managers/NavigationButtonsManager.ts

@@ -0,0 +1,71 @@
+import { IEventBus } from '../types/CalendarTypes';
+import { CoreEvents } from '../constants/CoreEvents';
+
+/**
+ * NavigationButtonsManager - Manages navigation button UI and state
+ *
+ * RESPONSIBILITY:
+ * ===============
+ * This manager owns all logic related to the <swp-nav-group> UI element.
+ * It follows the principle that each functional UI element has its own manager.
+ *
+ * RESPONSIBILITIES:
+ * - Handles button clicks on swp-nav-button elements
+ * - Validates navigation actions (prev, next, today)
+ * - Emits NAV_BUTTON_CLICKED events
+ * - Manages button UI listeners
+ *
+ * EVENT FLOW:
+ * ===========
+ * User clicks button → validateAction() → emit event → NavigationManager handles navigation
+ *
+ * SUBSCRIBERS:
+ * ============
+ * - NavigationManager: Performs actual navigation logic (animations, grid updates, week calculations)
+ */
+export class NavigationButtonsManager {
+  private eventBus: IEventBus;
+  private buttonListeners: Map<Element, EventListener> = new Map();
+
+  constructor(eventBus: IEventBus) {
+    this.eventBus = eventBus;
+    this.setupButtonListeners();
+  }
+
+  /**
+   * Setup click listeners on all navigation buttons
+   */
+  private setupButtonListeners(): void {
+    const buttons = document.querySelectorAll('swp-nav-button[data-action]');
+
+    buttons.forEach(button => {
+      const clickHandler = (event: Event) => {
+        event.preventDefault();
+        const action = button.getAttribute('data-action');
+        if (action && this.isValidAction(action)) {
+          this.handleNavigation(action);
+        }
+      };
+
+      button.addEventListener('click', clickHandler);
+      this.buttonListeners.set(button, clickHandler);
+    });
+  }
+
+  /**
+   * Handle navigation action
+   */
+  private handleNavigation(action: string): void {
+    // Emit navigation button clicked event
+    this.eventBus.emit(CoreEvents.NAV_BUTTON_CLICKED, {
+      action: action
+    });
+  }
+
+  /**
+   * Validate if string is a valid navigation action
+   */
+  private isValidAction(action: string): boolean {
+    return ['prev', 'next', 'today'].includes(action);
+  }
+}