update local startup flow and add root env example

Make the project start more reliably in the current Windows bash setup, add a safe root .env.example for onboarding, and lower the backend Python floor to 3.11 to match the validated local environment.

.env.example

@@ -0,0 +1,33 @@
+# =============================================
+# Jarvis 项目根配置
+# =============================================
+
+APP_NAME=Jarvis
+APP_VERSION=0.1.0
+DEBUG=true
+HOST=127.0.0.1
+PORT=3337
+SECRET_KEY=change-me-to-a-random-secret-key
+CORS_ORIGINS=["http://localhost:5173","http://localhost:3000"]
+
+# === 数据存储 ===
+DATABASE_URL=sqlite+aiosqlite:///./data/jarvis.db
+DATA_DIR=./data
+CHROMA_PERSIST_DIR=./data/chroma
+UPLOAD_DIR=./data/uploads
+MAX_UPLOAD_SIZE=52428800
+MINERU_LANGUAGE=ch
+
+# === JWT ===
+ACCESS_TOKEN_EXPIRE_MINUTES=1440
+
+# === 管理员账号 Bootstrap ===
+ADMIN=admin
+ADMIN_EMAIL=admin@example.com
+ADMIN_PASSWORD=change-me
+ADMIN_FULL_NAME=Administrator
+
+# === 定时任务 ===
+SCHEDULER_ENABLED=true
+DAILY_PLAN_TIME=00:00
+FORUM_SCAN_INTERVAL_MINUTES=30