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/scripts/load_memory_sample.py

@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+"""Load the Memory Settings review sample into a local DeerFlow runtime."""
+
+from __future__ import annotations
+
+import argparse
+import json
+import shutil
+from datetime import datetime
+from pathlib import Path
+
+
+def default_source(repo_root: Path) -> Path:
+    return repo_root / "backend" / "docs" / "memory-settings-sample.json"
+
+
+def default_target(repo_root: Path) -> Path:
+    return repo_root / "backend" / ".deer-flow" / "memory.json"
+
+
+def parse_args(repo_root: Path) -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description="Copy the Memory Settings sample data into the local runtime memory file.",
+    )
+    parser.add_argument(
+        "--source",
+        type=Path,
+        default=default_source(repo_root),
+        help="Path to the sample JSON file.",
+    )
+    parser.add_argument(
+        "--target",
+        type=Path,
+        default=default_target(repo_root),
+        help="Path to the runtime memory.json file.",
+    )
+    parser.add_argument(
+        "--no-backup",
+        action="store_true",
+        help="Overwrite the target without writing a backup copy first.",
+    )
+    return parser.parse_args()
+
+
+def validate_json_file(path: Path) -> None:
+    with path.open(encoding="utf-8") as handle:
+        json.load(handle)
+
+
+def main() -> int:
+    repo_root = Path(__file__).resolve().parents[1]
+    args = parse_args(repo_root)
+
+    source = args.source.resolve()
+    target = args.target.resolve()
+
+    if not source.exists():
+        raise SystemExit(f"Sample file not found: {source}")
+
+    validate_json_file(source)
+    target.parent.mkdir(parents=True, exist_ok=True)
+
+    backup_path: Path | None = None
+    if target.exists() and not args.no_backup:
+        timestamp = datetime.now().strftime("%Y%m%d-%H%M%S")
+        backup_path = target.with_name(f"{target.name}.bak-{timestamp}")
+        shutil.copy2(target, backup_path)
+
+    shutil.copy2(source, target)
+
+    print(f"Loaded sample memory into: {target}")
+    if backup_path is not None:
+        print(f"Backup created at: {backup_path}")
+    else:
+        print("No backup created.")
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())