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/frontend/scripts/save-demo.js

@@ -0,0 +1,61 @@
+import { config } from "dotenv";
+import fs from "fs";
+import path from "path";
+import { env } from "process";
+
+export async function main() {
+  const url = new URL(process.argv[2]);
+  const threadId = url.pathname.split("/").pop();
+  const host = url.host;
+  const apiURL = new URL(
+    `/api/langgraph/threads/${threadId}/history`,
+    `${url.protocol}//${host}`,
+  );
+  const response = await fetch(apiURL, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({
+      limit: 10,
+    }),
+  });
+
+  const data = (await response.json())[0];
+  if (!data) {
+    console.error("No data found");
+    return;
+  }
+
+  const title = data.values.title;
+
+  const rootPath = path.resolve(process.cwd(), "public/demo/threads", threadId);
+  if (fs.existsSync(rootPath)) {
+    fs.rmSync(rootPath, { recursive: true });
+  }
+  fs.mkdirSync(rootPath, { recursive: true });
+  fs.writeFileSync(
+    path.resolve(rootPath, "thread.json"),
+    JSON.stringify(data, null, 2),
+  );
+  const backendRootPath = path.resolve(
+    process.cwd(),
+    "../backend/.deer-flow/threads",
+    threadId,
+  );
+  copyFolder("user-data/outputs", rootPath, backendRootPath);
+  copyFolder("user-data/uploads", rootPath, backendRootPath);
+  console.info(`Saved demo "${title}" to ${rootPath}`);
+}
+
+function copyFolder(relPath, rootPath, backendRootPath) {
+  const outputsPath = path.resolve(backendRootPath, relPath);
+  if (fs.existsSync(outputsPath)) {
+    fs.cpSync(outputsPath, path.resolve(rootPath, relPath), {
+      recursive: true,
+    });
+  }
+}
+
+config();
+main();