Add SDK classes for managing benchmarks:

• Benchmark: Synchronous class for benchmark operations

  • get_info(): Retrieve benchmark details
  • update(): Update benchmark metadata
  • run(): Start a benchmark run, returns BenchmarkRun
  • add_scenarios(): Add scenarios to the benchmark
  • remove_scenarios(): Remove scenarios from the benchmark
  • list_runs(): List benchmark runs with filtering

• AsyncBenchmark: Async version with the same interface

• New TypedDicts for SDK params:

  • SDKBenchmarkUpdateParams
  • SDKBenchmarkStartRunParams
  • SDKBenchmarkListRunsParams

• Unit tests for both sync and async classes

• E2E smoketests