Adds audit logging and sync management infrastructure

Introduces comprehensive audit trail system with:
- AuditService to track entity changes
- SyncManager for background sync of audit entries
- New CoreEvents for entity and audit tracking
- Simplified sync architecture with event-driven approach

Prepares system for enhanced compliance and change tracking

src/storage/BaseEntityService.ts

@@ -2,6 +2,9 @@ import { ISync, EntityType, SyncStatus } from '../types/CalendarTypes';
 import { IEntityService } from './IEntityService';
 import { SyncPlugin } from './SyncPlugin';
 import { IndexedDBContext } from './IndexedDBContext';
+import { IEventBus } from '../types/CalendarTypes';
+import { CoreEvents } from '../constants/CoreEvents';
+import { diff } from 'json-diff-ts';
 
 /**
  * BaseEntityService<T extends ISync> - Abstract base class for all entity services
@@ -42,11 +45,16 @@ export abstract class BaseEntityService<T extends ISync> implements IEntityServi
   // IndexedDB context - provides database connection
   private context: IndexedDBContext;
 
+  // EventBus for emitting entity events
+  protected eventBus: IEventBus;
+
   /**
    * @param context - IndexedDBContext instance (injected dependency)
+   * @param eventBus - EventBus for emitting entity events
    */
-  constructor(context: IndexedDBContext) {
+  constructor(context: IndexedDBContext, eventBus: IEventBus) {
     this.context = context;
+    this.eventBus = eventBus;
     this.syncPlugin = new SyncPlugin<T>(this);
   }
 
@@ -132,10 +140,28 @@ export abstract class BaseEntityService<T extends ISync> implements IEntityServi
 
   /**
    * Save an entity (create or update)
+   * Emits ENTITY_SAVED event with operation type and changes
    *
    * @param entity - Entity to save
    */
   async save(entity: T): Promise<void> {
+    const entityId = (entity as any).id;
+
+    // Check if entity exists to determine create vs update
+    const existingEntity = await this.get(entityId);
+    const isCreate = existingEntity === null;
+
+    // Calculate changes: full entity for create, diff for update
+    let changes: any;
+    if (isCreate) {
+      changes = entity;
+    } else {
+      // Calculate diff between existing and new entity
+      const existingSerialized = this.serialize(existingEntity);
+      const newSerialized = this.serialize(entity);
+      changes = diff(existingSerialized, newSerialized);
+    }
+
     const serialized = this.serialize(entity);
 
     return new Promise((resolve, reject) => {
@@ -144,17 +170,26 @@ export abstract class BaseEntityService<T extends ISync> implements IEntityServi
       const request = store.put(serialized);
 
       request.onsuccess = () => {
+        // Emit ENTITY_SAVED event
+        this.eventBus.emit(CoreEvents.ENTITY_SAVED, {
+          entityType: this.entityType,
+          entityId,
+          operation: isCreate ? 'create' : 'update',
+          changes,
+          timestamp: Date.now()
+        });
         resolve();
       };
 
       request.onerror = () => {
-        reject(new Error(`Failed to save ${this.entityType} ${(entity as any).id}: ${request.error}`));
+        reject(new Error(`Failed to save ${this.entityType} ${entityId}: ${request.error}`));
       };
     });
   }
 
   /**
    * Delete an entity
+   * Emits ENTITY_DELETED event
    *
    * @param id - Entity ID to delete
    */
@@ -165,6 +200,13 @@ export abstract class BaseEntityService<T extends ISync> implements IEntityServi
       const request = store.delete(id);
 
       request.onsuccess = () => {
+        // Emit ENTITY_DELETED event
+        this.eventBus.emit(CoreEvents.ENTITY_DELETED, {
+          entityType: this.entityType,
+          entityId: id,
+          operation: 'delete',
+          timestamp: Date.now()
+        });
         resolve();
       };