fix: add filesystem middleware in init (#33955)

Author: sydney-runkle

libs/langchain_v1/langchain/agents/middleware/__init__.py

@@ -4,6 +4,7 @@
     ClearToolUsesEdit,
     ContextEditingMiddleware,
 )
+from .file_search import FilesystemFileSearchMiddleware
 from .human_in_the_loop import (
     HumanInTheLoopMiddleware,
     InterruptOnConfig,
@@ -46,6 +47,7 @@
     "CodexSandboxExecutionPolicy",
     "ContextEditingMiddleware",
     "DockerExecutionPolicy",
+    "FilesystemFileSearchMiddleware",
     "HostExecutionPolicy",
     "HumanInTheLoopMiddleware",
     "InterruptOnConfig",