chore(repo): consolidate local env and clean root files

.env.example

@@ -0,0 +1,31 @@
+# Copy to `.env` and fill real values before local backend runs or deploy work:
+#   cp .env.example .env
+
+# Backend runtime
+APP_JWT_SECRET="replace-with-at-least-32-bytes"
+APP_ADMIN_USERNAMES=""
+APP_AUTH_REGISTRATION_INVITE_CODE=""
+
+# DogeCloud API credentials
+YOYUZH_DOGECLOUD_API_BASE_URL="https://api.dogecloud.com"
+YOYUZH_DOGECLOUD_API_ACCESS_KEY="replace-me"
+YOYUZH_DOGECLOUD_API_SECRET_KEY="replace-me"
+YOYUZH_DOGECLOUD_S3_REGION="automatic"
+
+# Frontend / storage deploy scopes
+YOYUZH_DOGECLOUD_FRONT_SCOPE="yoyuzh-front"
+YOYUZH_DOGECLOUD_FRONT_TTL_SECONDS="3600"
+YOYUZH_DOGECLOUD_FRONT_PREFIX=""
+YOYUZH_DOGECLOUD_STORAGE_SCOPE="yoyuzh-files"
+YOYUZH_DOGECLOUD_STORAGE_TTL_SECONDS="3600"
+YOYUZH_DOGECLOUD_ANDROID_SCOPE="yoyuzh-files"
+YOYUZH_ANDROID_RELEASE_PREFIX="android/releases"
+
+# Server access and deploy metadata
+YOYUZH_SERVER_HOST="replace-me"
+YOYUZH_SERVER_USER="replace-me"
+YOYUZH_SERVER_PASSWORD="replace-me"
+YOYUZH_BACKEND_SYSTEMD_SERVICE="my-site-api.service"
+YOYUZH_BACKEND_REMOTE_JAR_PATH="/opt/yoyuzh/yoyuzh-portal-backend.jar"
+YOYUZH_BACKEND_REMOTE_ENV_FILE="/opt/yoyuzh/app.env"
+YOYUZH_BACKEND_REMOTE_CONFIG="/opt/yoyuzh/application-prod.yml"