Initial commit: hardened DeerFlow factory

Vendored deer-flow upstream (bytedance/deer-flow) plus prompt-injection
hardening:

- New deerflow.security package: content_delimiter, html_cleaner,
  sanitizer (8 layers — invisible chars, control chars, symbols, NFC,
  PUA, tag chars, horizontal whitespace collapse with newline/tab
  preservation, length cap)
- New deerflow.community.searx package: web_search, web_fetch,
  image_search backed by a private SearX instance, every external
  string sanitized and wrapped in <<<EXTERNAL_UNTRUSTED_CONTENT>>>
  delimiters
- All native community web providers (ddg_search, tavily, exa,
  firecrawl, jina_ai, infoquest, image_search) replaced with hard-fail
  stubs that raise NativeWebToolDisabledError at import time, so a
  misconfigured tool.use path fails loud rather than silently falling
  back to unsanitized output
- Native client back-doors (jina_client.py, infoquest_client.py)
  stubbed too
- Native-tool tests quarantined under tests/_disabled_native/
  (collect_ignore_glob via local conftest.py)
- Sanitizer Layer 7 fix: only collapse horizontal whitespace, preserve
  newlines and tabs so list/table structure survives
- Hardened runtime config.yaml references only the searx-backed tools
- Factory overlay (backend/) kept in sync with deer-flow tree as a
  reference / source

See HARDENING.md for the full audit trail and verification steps.

deer-flow/skills/public/chart-visualization/references/generate_pin_map.md

@@ -0,0 +1,23 @@
+# generate_pin_map — 点标地图（中国）
+
+## 功能概述
+在中国地图上以标记展示多个 POI 位置，可配合弹窗显示图片或说明，适用于门店分布、资产布点等。
+
+## 输入字段
+### 必填
+- `title`: string，必填且≤16 字，概述点位集合。
+- `data`: string[]，必填，包含中国境内的 POI 名称列表。
+
+### 可选
+- `markerPopup.type`: string，固定为 `image`。
+- `markerPopup.width`: number，默认 `40`，图片宽度。
+- `markerPopup.height`: number，默认 `40`，图片高度。
+- `markerPopup.borderRadius`: number，默认 `8`，图片圆角。
+- `width`: number，默认 `1600`。
+- `height`: number，默认 `1000`。
+
+## 使用建议
+POI 名称需包含足够的地理限定（城市+地标）；根据业务可在名称中附带属性，如“上海徐汇门店 A”；地图依赖高德数据，仅支持中国。
+
+## 返回结果
+- 返回点标地图 URL，并在 `_meta.spec` 中保存点位与弹窗配置。