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/.agent/skills/smoke-test/scripts/pull_code.sh

@@ -0,0 +1,49 @@
+#!/usr/bin/env bash
+set -e
+
+echo "=========================================="
+echo "  Pulling the Latest Code"
+echo "=========================================="
+echo ""
+
+# Check whether the current directory is a Git repository
+if [ ! -d ".git" ]; then
+    echo "✗ The current directory is not a Git repository"
+    exit 1
+fi
+
+# Check Git status
+echo "Checking Git status..."
+if git status --porcelain | grep -q .; then
+    echo "⚠  Uncommitted changes detected:"
+    git status --short
+    echo ""
+    echo "Please commit or stash your changes before continuing"
+    echo "Options:"
+    echo "  1. git add . && git commit -m 'Save changes'"
+    echo "  2. git stash (stash changes and restore them later)"
+    echo "  3. git reset --hard HEAD (discard local changes - use with caution)"
+    exit 1
+else
+    echo "✓ Working tree is clean"
+fi
+echo ""
+
+# Fetch remote updates
+echo "Fetching remote updates..."
+git fetch origin main
+echo ""
+
+# Pull the latest code
+echo "Pulling the latest code..."
+git pull origin main
+echo ""
+
+# Show the latest commit
+echo "Latest commit:"
+git log -1 --oneline
+echo ""
+
+echo "=========================================="
+echo "  Code Update Complete"
+echo "=========================================="