chore: initial monorepo scaffold

Setup pnpm workspaces with apps/{web,api} placeholders and shared
packages: tsconfig, eslint-config, shared, ui, db. Includes Prettier,
ESLint, Husky pre-commit, lint-staged, EditorConfig, VSCode settings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shared/tsconfig.json

@@ -0,0 +1,10 @@
+{
+  "extends": "@ketopath/tsconfig/base.json",
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src",
+    "composite": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}