chore: initial repository scaffolding

- Add README with features, quick-start (local + Docker) and docs index
- Add MIT LICENSE, root .gitignore and .env.example
- Add docker-compose.yml (postgres + backend + frontend)
- Add root package.json with install:all/dev helpers
- Add Gitea CI workflow (backend syntax check, frontend build)

.gitignore

@@ -0,0 +1,6 @@
+node_modules/
+dist/
+.env
+*.log
+.DS_Store
+coverage/