feat(#1): Set up monorepo scaffold with pnpm workspaces + TurboRepo

Implements the foundational project structure including:
- pnpm workspaces configuration
- TurboRepo for build orchestration
- NestJS 11.1.12 API (apps/api)
- Next.js 16.1.6 web app (apps/web)
- Shared packages (config, shared, ui)
- TypeScript strict mode configuration
- ESLint + Prettier setup
- Vitest for unit testing (19 passing tests)

Fixes #1

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

packages/shared/package.json

@@ -0,0 +1,40 @@
+{
+  "name": "@mosaic/shared",
+  "version": "0.0.1",
+  "private": true,
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "require": "./dist/index.js",
+      "import": "./dist/index.js"
+    },
+    "./types": {
+      "types": "./dist/types/index.d.ts",
+      "require": "./dist/types/index.js",
+      "import": "./dist/types/index.js"
+    },
+    "./utils": {
+      "types": "./dist/utils/index.d.ts",
+      "require": "./dist/utils/index.js",
+      "import": "./dist/utils/index.js"
+    }
+  },
+  "scripts": {
+    "build": "tsc",
+    "dev": "tsc --watch",
+    "lint": "eslint src/",
+    "lint:fix": "eslint src/ --fix",
+    "typecheck": "tsc --noEmit",
+    "clean": "rm -rf dist",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:coverage": "vitest run --coverage"
+  },
+  "devDependencies": {
+    "@mosaic/config": "workspace:*",
+    "typescript": "^5.8.2",
+    "vitest": "^3.0.8"
+  }
+}

packages/shared/src/index.ts

@@ -0,0 +1,2 @@
+export * from "./types/index";
+export * from "./utils/index";

packages/shared/src/types/index.ts

@@ -0,0 +1,38 @@
+/**
+ * Base entity type with common fields
+ */
+export interface BaseEntity {
+  id: string;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+/**
+ * API response wrapper
+ */
+export interface ApiResponse<T> {
+  data: T;
+  success: boolean;
+  message?: string;
+}
+
+/**
+ * Pagination parameters
+ */
+export interface PaginationParams {
+  page: number;
+  limit: number;
+  sortBy?: string;
+  sortOrder?: "asc" | "desc";
+}
+
+/**
+ * Paginated response
+ */
+export interface PaginatedResponse<T> {
+  data: T[];
+  total: number;
+  page: number;
+  limit: number;
+  totalPages: number;
+}

packages/shared/src/utils/index.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, it } from "vitest";
+import { isDefined, parseDate, sleep, slugify } from "./index.js";
+
+describe("parseDate", () => {
+  it("should return undefined for null or undefined", () => {
+    expect(parseDate(null)).toBeUndefined();
+    expect(parseDate(undefined)).toBeUndefined();
+  });
+
+  it("should return the same Date object if passed a Date", () => {
+    const date = new Date("2024-01-15");
+    expect(parseDate(date)).toBe(date);
+  });
+
+  it("should parse valid date strings", () => {
+    const result = parseDate("2024-01-15");
+    expect(result).toBeInstanceOf(Date);
+    expect(result?.toISOString()).toContain("2024-01-15");
+  });
+
+  it("should return undefined for invalid date strings", () => {
+    expect(parseDate("not-a-date")).toBeUndefined();
+  });
+});
+
+describe("slugify", () => {
+  it("should convert text to lowercase slug", () => {
+    expect(slugify("Hello World")).toBe("hello-world");
+  });
+
+  it("should handle special characters", () => {
+    expect(slugify("Hello, World!")).toBe("hello-world");
+  });
+
+  it("should trim leading and trailing hyphens", () => {
+    expect(slugify("  Hello World  ")).toBe("hello-world");
+  });
+});
+
+describe("sleep", () => {
+  it("should resolve after the specified time", async () => {
+    const start = Date.now();
+    await sleep(50);
+    const elapsed = Date.now() - start;
+    expect(elapsed).toBeGreaterThanOrEqual(45);
+  });
+});
+
+describe("isDefined", () => {
+  it("should return false for null and undefined", () => {
+    expect(isDefined(null)).toBe(false);
+    expect(isDefined(undefined)).toBe(false);
+  });
+
+  it("should return true for defined values", () => {
+    expect(isDefined(0)).toBe(true);
+    expect(isDefined("")).toBe(true);
+    expect(isDefined(false)).toBe(true);
+    expect(isDefined({})).toBe(true);
+  });
+});

packages/shared/src/utils/index.ts

@@ -0,0 +1,35 @@
+/**
+ * Safely parse a date string or return undefined
+ */
+export function parseDate(value: string | Date | undefined | null): Date | undefined {
+  if (!value) return undefined;
+  if (value instanceof Date) return value;
+  const parsed = new Date(value);
+  return isNaN(parsed.getTime()) ? undefined : parsed;
+}
+
+/**
+ * Generate a simple slug from a string
+ */
+export function slugify(text: string): string {
+  return text
+    .toLowerCase()
+    .trim()
+    .replace(/[^\w\s-]/g, "")
+    .replace(/[\s_-]+/g, "-")
+    .replace(/^-+|-+$/g, "");
+}
+
+/**
+ * Sleep for a given number of milliseconds
+ */
+export function sleep(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+/**
+ * Check if a value is defined (not null or undefined)
+ */
+export function isDefined<T>(value: T | null | undefined): value is T {
+  return value !== null && value !== undefined;
+}

packages/shared/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "extends": "@mosaic/config/typescript/library",
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src",
+    "module": "CommonJS",
+    "moduleResolution": "node",
+    "lib": ["ES2022", "DOM"]
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist", "**/*.test.ts"]
+}

packages/shared/vitest.config.ts

@@ -0,0 +1,14 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    globals: false,
+    environment: "node",
+    include: ["src/**/*.test.ts"],
+    coverage: {
+      provider: "v8",
+      reporter: ["text", "json", "html"],
+      exclude: ["node_modules/", "dist/"],
+    },
+  },
+});