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/events/dto/create-event.dto.ts

@@ -0,0 +1,53 @@
+import {
+  IsString,
+  IsOptional,
+  IsUUID,
+  IsDateString,
+  IsBoolean,
+  IsObject,
+  MinLength,
+  MaxLength,
+} from "class-validator";
+
+/**
+ * DTO for creating a new event
+ */
+export class CreateEventDto {
+  @IsString({ message: "title must be a string" })
+  @MinLength(1, { message: "title must not be empty" })
+  @MaxLength(255, { message: "title must not exceed 255 characters" })
+  title!: string;
+
+  @IsOptional()
+  @IsString({ message: "description must be a string" })
+  @MaxLength(10000, { message: "description must not exceed 10000 characters" })
+  description?: string;
+
+  @IsDateString({}, { message: "startTime must be a valid ISO 8601 date string" })
+  startTime!: Date;
+
+  @IsOptional()
+  @IsDateString({}, { message: "endTime must be a valid ISO 8601 date string" })
+  endTime?: Date;
+
+  @IsOptional()
+  @IsBoolean({ message: "allDay must be a boolean" })
+  allDay?: boolean;
+
+  @IsOptional()
+  @IsString({ message: "location must be a string" })
+  @MaxLength(500, { message: "location must not exceed 500 characters" })
+  location?: string;
+
+  @IsOptional()
+  @IsObject({ message: "recurrence must be an object" })
+  recurrence?: Record<string, unknown>;
+
+  @IsOptional()
+  @IsUUID("4", { message: "projectId must be a valid UUID" })
+  projectId?: string;
+
+  @IsOptional()
+  @IsObject({ message: "metadata must be an object" })
+  metadata?: Record<string, unknown>;
+}

apps/api/src/events/dto/index.ts

@@ -0,0 +1,3 @@
+export { CreateEventDto } from "./create-event.dto";
+export { UpdateEventDto } from "./update-event.dto";
+export { QueryEventsDto } from "./query-events.dto";

apps/api/src/events/dto/query-events.dto.ts

@@ -0,0 +1,48 @@
+import {
+  IsUUID,
+  IsOptional,
+  IsInt,
+  Min,
+  Max,
+  IsDateString,
+  IsBoolean,
+} from "class-validator";
+import { Type } from "class-transformer";
+
+/**
+ * DTO for querying events with filters and pagination
+ */
+export class QueryEventsDto {
+  @IsUUID("4", { message: "workspaceId must be a valid UUID" })
+  workspaceId!: string;
+
+  @IsOptional()
+  @IsUUID("4", { message: "projectId must be a valid UUID" })
+  projectId?: string;
+
+  @IsOptional()
+  @IsDateString({}, { message: "startFrom must be a valid ISO 8601 date string" })
+  startFrom?: Date;
+
+  @IsOptional()
+  @IsDateString({}, { message: "startTo must be a valid ISO 8601 date string" })
+  startTo?: Date;
+
+  @IsOptional()
+  @IsBoolean({ message: "allDay must be a boolean" })
+  @Type(() => Boolean)
+  allDay?: boolean;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt({ message: "page must be an integer" })
+  @Min(1, { message: "page must be at least 1" })
+  page?: number;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt({ message: "limit must be an integer" })
+  @Min(1, { message: "limit must be at least 1" })
+  @Max(100, { message: "limit must not exceed 100" })
+  limit?: number;
+}

apps/api/src/events/dto/update-event.dto.ts

@@ -0,0 +1,56 @@
+import {
+  IsString,
+  IsOptional,
+  IsUUID,
+  IsDateString,
+  IsBoolean,
+  IsObject,
+  MinLength,
+  MaxLength,
+} from "class-validator";
+
+/**
+ * DTO for updating an existing event
+ * All fields are optional to support partial updates
+ */
+export class UpdateEventDto {
+  @IsOptional()
+  @IsString({ message: "title must be a string" })
+  @MinLength(1, { message: "title must not be empty" })
+  @MaxLength(255, { message: "title must not exceed 255 characters" })
+  title?: string;
+
+  @IsOptional()
+  @IsString({ message: "description must be a string" })
+  @MaxLength(10000, { message: "description must not exceed 10000 characters" })
+  description?: string | null;
+
+  @IsOptional()
+  @IsDateString({}, { message: "startTime must be a valid ISO 8601 date string" })
+  startTime?: Date;
+
+  @IsOptional()
+  @IsDateString({}, { message: "endTime must be a valid ISO 8601 date string" })
+  endTime?: Date | null;
+
+  @IsOptional()
+  @IsBoolean({ message: "allDay must be a boolean" })
+  allDay?: boolean;
+
+  @IsOptional()
+  @IsString({ message: "location must be a string" })
+  @MaxLength(500, { message: "location must not exceed 500 characters" })
+  location?: string | null;
+
+  @IsOptional()
+  @IsObject({ message: "recurrence must be an object" })
+  recurrence?: Record<string, unknown> | null;
+
+  @IsOptional()
+  @IsUUID("4", { message: "projectId must be a valid UUID" })
+  projectId?: string | null;
+
+  @IsOptional()
+  @IsObject({ message: "metadata must be an object" })
+  metadata?: Record<string, unknown>;
+}