Replace benchmark.cc with a Python script

[zhanglei1949]

Background

bin/benchmark.cc directly uses google::protobuf::Arena to allocate QueryResponse messages. Because libneug.so hides all protobuf symbols via the version script (cmake/neug_exports.ld), the benchmark binary cannot link ${Protobuf_LIBRARIES} without causing duplicate libprotobuf runtime issues (#387).

PR #491 removed the explicit protobuf linkage from all other consumer targets, but benchmark.cc still has direct Arena usage that needs to be addressed.

Proposal

Replace bin/benchmark.cc with a Python script that uses neug_py_bind to run benchmarks. This:

• Eliminates the last direct protobuf dependency in consumer binaries
• Simplifies the build matrix (benchmark target can be removed from bin/CMakeLists.txt)
• Makes benchmarks easier to extend and parameterize without recompilation
• Leverages the existing Python binding infrastructure

Scope

• Port benchmark.cc functionality to a Python script (config parsing, query execution loop, timing)
• Remove benchmark.cc and its CMake target from bin/CMakeLists.txt
• Verify equivalent performance measurement accuracy through Python bindings

Related

• [BUG] Duplicate libprotobuf runtime in benchmark/rt_server causes descriptor pool failures #387 — duplicate libprotobuf runtime bug
• refactor: remove explicit ${Protobuf_LIBRARIES} linkage from consumer targets #490 — remove explicit ${Protobuf_LIBRARIES} linkage
• refactor: Forbid all linkage to protobuf for binaries #491 — PR removing protobuf linkage from other targets

[github-actions]

🤖 Auto-triage: linked as sub-issue of #257 — Grouping adhoc issues (confidence: high).

Reason: The issue is an isolated build-system and testing-infrastructure refactor to replace a C++ benchmark binary with a Python script, fitting the adhoc CI/build-infra scope of #257.

Auto-applied: type → Task; labels → ci

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