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/frontend_check.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+set +e
+
+echo "=========================================="
+echo "  Frontend Page Smoke Check"
+echo "=========================================="
+echo ""
+
+BASE_URL="${BASE_URL:-http://localhost:2026}"
+DOC_PATH="${DOC_PATH:-/en/docs}"
+
+all_passed=true
+
+check_status() {
+    local name="$1"
+    local url="$2"
+    local expected_re="$3"
+
+    local status
+    status="$(curl -s -o /dev/null -w "%{http_code}" -L "$url")"
+    if echo "$status" | grep -Eq "$expected_re"; then
+        echo "✓ $name ($url) -> $status"
+    else
+        echo "✗ $name ($url) -> $status (expected: $expected_re)"
+        all_passed=false
+    fi
+}
+
+check_final_url() {
+    local name="$1"
+    local url="$2"
+    local expected_path_re="$3"
+
+    local effective
+    effective="$(curl -s -o /dev/null -w "%{url_effective}" -L "$url")"
+    if echo "$effective" | grep -Eq "$expected_path_re"; then
+        echo "✓ $name redirect target -> $effective"
+    else
+        echo "✗ $name redirect target -> $effective (expected path: $expected_path_re)"
+        all_passed=false
+    fi
+}
+
+echo "1. Checking entry pages..."
+check_status "Landing page" "${BASE_URL}/" "200"
+check_status "Workspace redirect" "${BASE_URL}/workspace" "200|301|302|307|308"
+check_final_url "Workspace redirect" "${BASE_URL}/workspace" "/workspace/chats/"
+echo ""
+
+echo "2. Checking key workspace routes..."
+check_status "New chat page" "${BASE_URL}/workspace/chats/new" "200"
+check_status "Chats list page" "${BASE_URL}/workspace/chats" "200"
+check_status "Agents gallery page" "${BASE_URL}/workspace/agents" "200"
+echo ""
+
+echo "3. Checking docs route (optional)..."
+check_status "Docs page" "${BASE_URL}${DOC_PATH}" "200|404"
+echo ""
+
+echo "=========================================="
+echo "  Frontend Smoke Check Summary"
+echo "=========================================="
+echo ""
+if [ "$all_passed" = true ]; then
+    echo "✅ Frontend smoke checks passed!"
+    exit 0
+else
+    echo "❌ Frontend smoke checks failed"
+    exit 1
+fi