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/backend/packages/harness/deerflow/sandbox/exceptions.py

@@ -0,0 +1,71 @@
+"""Sandbox-related exceptions with structured error information."""
+
+
+class SandboxError(Exception):
+    """Base exception for all sandbox-related errors."""
+
+    def __init__(self, message: str, details: dict | None = None):
+        super().__init__(message)
+        self.message = message
+        self.details = details or {}
+
+    def __str__(self) -> str:
+        if self.details:
+            detail_str = ", ".join(f"{k}={v}" for k, v in self.details.items())
+            return f"{self.message} ({detail_str})"
+        return self.message
+
+
+class SandboxNotFoundError(SandboxError):
+    """Raised when a sandbox cannot be found or is not available."""
+
+    def __init__(self, message: str = "Sandbox not found", sandbox_id: str | None = None):
+        details = {"sandbox_id": sandbox_id} if sandbox_id else None
+        super().__init__(message, details)
+        self.sandbox_id = sandbox_id
+
+
+class SandboxRuntimeError(SandboxError):
+    """Raised when sandbox runtime is not available or misconfigured."""
+
+    pass
+
+
+class SandboxCommandError(SandboxError):
+    """Raised when a command execution fails in the sandbox."""
+
+    def __init__(self, message: str, command: str | None = None, exit_code: int | None = None):
+        details = {}
+        if command:
+            details["command"] = command[:100] + "..." if len(command) > 100 else command
+        if exit_code is not None:
+            details["exit_code"] = exit_code
+        super().__init__(message, details)
+        self.command = command
+        self.exit_code = exit_code
+
+
+class SandboxFileError(SandboxError):
+    """Raised when a file operation fails in the sandbox."""
+
+    def __init__(self, message: str, path: str | None = None, operation: str | None = None):
+        details = {}
+        if path:
+            details["path"] = path
+        if operation:
+            details["operation"] = operation
+        super().__init__(message, details)
+        self.path = path
+        self.operation = operation
+
+
+class SandboxPermissionError(SandboxFileError):
+    """Raised when a permission error occurs during file operations."""
+
+    pass
+
+
+class SandboxFileNotFoundError(SandboxFileError):
+    """Raised when a file or directory is not found."""
+
+    pass