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/config/eslint/base.js

@@ -0,0 +1,32 @@
+import eslint from "@eslint/js";
+import tseslint from "typescript-eslint";
+import prettierConfig from "eslint-config-prettier";
+import prettierPlugin from "eslint-plugin-prettier";
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  ...tseslint.configs.strictTypeChecked,
+  ...tseslint.configs.stylisticTypeChecked,
+  prettierConfig,
+  {
+    plugins: {
+      prettier: prettierPlugin,
+    },
+    rules: {
+      "prettier/prettier": "error",
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        { argsIgnorePattern: "^_", varsIgnorePattern: "^_" },
+      ],
+      "@typescript-eslint/consistent-type-imports": [
+        "error",
+        { prefer: "type-imports" },
+      ],
+      "@typescript-eslint/no-floating-promises": "error",
+      "@typescript-eslint/no-misused-promises": "error",
+    },
+  },
+  {
+    ignores: ["**/node_modules/**", "**/dist/**", "**/.next/**", "**/coverage/**"],
+  }
+);

packages/config/eslint/nestjs.js

@@ -0,0 +1,12 @@
+import baseConfig from "./base.js";
+
+export default [
+  ...baseConfig,
+  {
+    rules: {
+      "@typescript-eslint/interface-name-prefix": "off",
+      "@typescript-eslint/explicit-function-return-type": "off",
+      "@typescript-eslint/explicit-module-boundary-types": "off",
+    },
+  },
+];

packages/config/eslint/nextjs.js

@@ -0,0 +1,17 @@
+import baseConfig from "./base.js";
+
+export default [
+  ...baseConfig,
+  {
+    rules: {
+      "@typescript-eslint/no-misused-promises": [
+        "error",
+        {
+          checksVoidReturn: {
+            attributes: false,
+          },
+        },
+      ],
+    },
+  },
+];

packages/config/package.json

@@ -0,0 +1,29 @@
+{
+  "name": "@mosaic/config",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "exports": {
+    "./typescript/base": "./typescript/base.json",
+    "./typescript/nextjs": "./typescript/nextjs.json",
+    "./typescript/nestjs": "./typescript/nestjs.json",
+    "./typescript/library": "./typescript/library.json",
+    "./eslint/base": "./eslint/base.js",
+    "./eslint/nextjs": "./eslint/nextjs.js",
+    "./eslint/nestjs": "./eslint/nestjs.js",
+    "./prettier": "./prettier/index.js"
+  },
+  "dependencies": {
+    "@eslint/js": "^9.21.0",
+    "@typescript-eslint/eslint-plugin": "^8.26.0",
+    "@typescript-eslint/parser": "^8.26.0",
+    "eslint": "^9.21.0",
+    "eslint-config-prettier": "^10.1.0",
+    "eslint-plugin-prettier": "^5.2.3",
+    "prettier": "^3.5.3",
+    "typescript-eslint": "^8.26.0"
+  },
+  "devDependencies": {
+    "typescript": "^5.8.2"
+  }
+}

packages/config/prettier/index.js

@@ -0,0 +1,13 @@
+/** @type {import("prettier").Config} */
+const config = {
+  semi: true,
+  singleQuote: false,
+  tabWidth: 2,
+  trailingComma: "es5",
+  printWidth: 100,
+  bracketSpacing: true,
+  arrowParens: "always",
+  endOfLine: "lf",
+};
+
+export default config;

packages/config/typescript/base.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "compilerOptions": {
+    "strict": true,
+    "strictNullChecks": true,
+    "strictFunctionTypes": true,
+    "strictBindCallApply": true,
+    "strictPropertyInitialization": true,
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUncheckedIndexedAccess": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "exactOptionalPropertyTypes": true,
+    "forceConsistentCasingInFileNames": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true,
+    "target": "ES2022",
+    "module": "ESNext",
+    "lib": ["ES2022"]
+  }
+}

packages/config/typescript/library.json

@@ -0,0 +1,7 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "extends": "./base.json",
+  "compilerOptions": {
+    "composite": true
+  }
+}

packages/config/typescript/nestjs.json

@@ -0,0 +1,12 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "extends": "./base.json",
+  "compilerOptions": {
+    "module": "CommonJS",
+    "moduleResolution": "node",
+    "emitDecoratorMetadata": true,
+    "experimentalDecorators": true,
+    "incremental": true,
+    "target": "ES2022"
+  }
+}

packages/config/typescript/nextjs.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "extends": "./base.json",
+  "compilerOptions": {
+    "lib": ["DOM", "DOM.Iterable", "ES2022"],
+    "jsx": "preserve",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "allowJs": true,
+    "noEmit": true,
+    "incremental": true,
+    "plugins": [
+      {
+        "name": "next"
+      }
+    ]
+  }
+}