Feat: Benchmark CLI additions and documentation (#12536)

### What problem does this PR solve?

This PR adds a dedicated HTTP benchmark CLI for RAGFlow chat and
retrieval endpoints so we can measure latency/QPS.

### Type of change

- [x] Documentation Update
- [x] Other (please describe): Adds a CLI benchmarking tool for
chat/retrieval latency/QPS

---------

Co-authored-by: Liu An <asiro@qq.com>

uv.lock

@@ -6174,6 +6174,7 @@ test = [
     { name = "hypothesis" },
     { name = "openpyxl" },
     { name = "pillow" },
+    { name = "pycryptodomex" },
     { name = "pytest" },
     { name = "pytest-asyncio" },
     { name = "pytest-cov" },
@@ -6307,6 +6308,7 @@ test = [
     { name = "hypothesis", specifier = ">=6.132.0" },
     { name = "openpyxl", specifier = ">=3.1.5" },
     { name = "pillow", specifier = ">=10.4.0,<13.0.0" },
+    { name = "pycryptodomex", specifier = "==3.20.0" },
     { name = "pytest", specifier = ">=8.3.5" },
     { name = "pytest-asyncio", specifier = ">=1.3.0" },
     { name = "pytest-cov", specifier = ">=7.0.0" },