feat: SearXNG 搜索集成 + DevTools Docker + PG 备份 + 文档更新

- web_search 工具/插件接入自托管 SearXNG，支持百度/必应/搜狗/360搜索
- DevTools 加入 docker-compose.dev.yml，devtools/Dockerfile
- scripts/pg-backup.sh 数据库备份恢复脚本，docs/pg-backup-migration.md
- 后台思考 + datetime 插件时区默认 Asia/Shanghai
- docker-compose 对齐 volume 名称，清理 tool-engine 残留引用
- README.md / Deploy.md 更新至当前架构（移除简报/tool-engine，新增搜索/跨端同步/DevTools）

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/pg-backup.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+# Cyrene PostgreSQL 备份/恢复
+# 用法: ./pg-backup.sh backup   # 备份到 ./backups/
+#       ./pg-backup.sh restore  # 从最新备份恢复
+set -euo pipefail
+
+CONTAINER="cyrene_postgres"
+DB="cyrene_ai"
+USER="cyrene"
+BACKUP_DIR="$(cd "$(dirname "$0")/../backups" && pwd)"
+
+backup() {
+  mkdir -p "$BACKUP_DIR"
+  local file="$BACKUP_DIR/cyrene_$(date +%Y%m%d_%H%M%S).sql"
+  echo "正在备份 $DB → $file ..."
+  docker exec "$CONTAINER" pg_dump -U "$USER" -d "$DB" \
+    --no-owner --no-acl --clean --if-exists > "$file"
+  ls -lh "$file"
+  echo "备份完成: $file"
+
+  # 只保留最近 7 个备份
+  local count=$(ls -1 "$BACKUP_DIR"/*.sql 2>/dev/null | wc -l)
+  if [ "$count" -gt 7 ]; then
+    ls -1t "$BACKUP_DIR"/*.sql | tail -n +8 | xargs rm -f
+    echo "已清理旧备份 (保留最近 7 个)"
+  fi
+}
+
+restore() {
+  local file
+  if [ -n "${1:-}" ]; then
+    file="$1"
+  else
+    file=$(ls -1t "$BACKUP_DIR"/*.sql 2>/dev/null | head -1)
+  fi
+  if [ -z "$file" ] || [ ! -f "$file" ]; then
+    echo "错误: 找不到备份文件" >&2
+    exit 1
+  fi
+  echo "正在从 $file 恢复..."
+  docker exec -i "$CONTAINER" psql -U "$USER" -d "$DB" < "$file"
+  echo "恢复完成"
+}
+
+case "${1:-}" in
+  backup)  backup ;;
+  restore) restore "${2:-}" ;;
+  *)
+    echo "用法: $0 backup|restore [文件路径]"
+    echo "  backup         备份到 $BACKUP_DIR"
+    echo "  restore [file] 恢复备份 (默认最新)"
+    exit 1
+    ;;
+esac