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>

.vscode/settings.json

@@ -0,0 +1,11 @@
+{
+  "editor.formatOnSave": true,
+  "editor.defaultFormatter": "esbenp.prettier-vscode",
+  "editor.codeActionsOnSave": {
+    "source.fixAll.eslint": "explicit"
+  },
+  "eslint.workingDirectories": [{ "pattern": "apps/*" }, { "pattern": "packages/*" }],
+  "typescript.tsdk": "node_modules/typescript/lib",
+  "typescript.enablePromptUseWorkspaceTsdk": true,
+  "files.eol": "\n"
+}