fix: panel init without werkzeug; stop tracking .env

Use stdlib pbkdf2 for admin passwords so init_db works reliably.
Remove .env from git to avoid pull conflicts on VPS.
Verify flask install before database init.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/install.sh

@@ -140,7 +140,10 @@ nginx -t && systemctl enable nginx && systemctl restart nginx
 
 log "安装 Python 面板依赖 ..."
 python3 -m venv "$ROOT_DIR/panel/venv"
+"$ROOT_DIR/panel/venv/bin/pip" install -q --upgrade pip
 "$ROOT_DIR/panel/venv/bin/pip" install -q -r "$ROOT_DIR/panel/requirements.txt"
+"$ROOT_DIR/panel/venv/bin/python" -c "import flask" \
+  || err "面板依赖安装失败，请检查网络后重试"
 
 log "初始化节点数据库 ..."
 "$ROOT_DIR/panel/venv/bin/python" "$ROOT_DIR/panel/init_db.py"