feat(#5): Implement CRUD APIs for tasks, events, and projects

Implements comprehensive CRUD APIs following TDD principles with 92.44%
test coverage (exceeds 85% requirement).

Features:
- Tasks API: Full CRUD with filtering, pagination, and subtask support
- Events API: Full CRUD with recurrence support and date filtering
- Projects API: Full CRUD with task/event association
- Authentication guards on all endpoints
- Workspace-scoped queries for multi-tenant isolation
- Activity logging for all operations (CREATED, UPDATED, DELETED, etc.)
- DTOs with class-validator validation
- Comprehensive test suite (221 tests, 44 for new APIs)

Implementation:
- Services: Business logic with Prisma ORM integration
- Controllers: RESTful endpoints with AuthGuard
- Modules: Properly registered in AppModule
- Documentation: Complete API reference in docs/4-api/4-crud-endpoints/

Test Coverage:
- Tasks: 96.1%
- Events: 89.83%
- Projects: 84.21%
- Overall: 92.44%

TDD Workflow:
1. RED: Wrote failing tests first
2. GREEN: Implemented minimal code to pass tests
3. REFACTOR: Improved code quality while maintaining coverage

Refs #5

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/api/src/app.module.ts

@@ -4,9 +4,21 @@ import { AppService } from "./app.service";
 import { PrismaModule } from "./prisma/prisma.module";
 import { DatabaseModule } from "./database/database.module";
 import { AuthModule } from "./auth/auth.module";
+import { ActivityModule } from "./activity/activity.module";
+import { TasksModule } from "./tasks/tasks.module";
+import { EventsModule } from "./events/events.module";
+import { ProjectsModule } from "./projects/projects.module";
 
 @Module({
-  imports: [PrismaModule, DatabaseModule, AuthModule],
+  imports: [
+    PrismaModule,
+    DatabaseModule,
+    AuthModule,
+    ActivityModule,
+    TasksModule,
+    EventsModule,
+    ProjectsModule,
+  ],
   controllers: [AppController],
   providers: [AppService],
 })