feat: initial dev-configs monorepo

Shared configs for TypeScript projects: ESLint, Prettier, TypeScript,
Vite, Jest, Playwright, Knip. Published as @vigdorov/* npm packages
to Gitea registry.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,13 @@
+{
+    "name": "dev-configs",
+    "private": true,
+    "workspaces": [
+        "packages/*"
+    ],
+    "scripts": {
+        "build": "npm run build -ws --if-present",
+        "test": "npm run test -ws --if-present",
+        "lint": "npm run lint -ws --if-present",
+        "check": "npm run check -ws --if-present"
+    }
+}