feat: Add context size support for benchmarks and update example usage

This commit adds support for specifying context size when running benchmarks, which is passed to the Ollama client as the `num_ctx` option. The changes include:

- Updated the `run` method in the base benchmark class to accept an optional `context_size` parameter
- Modified the Ollama client call to include context size in the options when provided
- Updated the `run_benchmarks` function to accept and pass through the context size
- Added example usage to the help output showing how to use the new context size parameter
- Fixed prompt formatting in the summarization benchmark to use `text` instead of `task`

The changes enable running benchmarks with custom context sizes, which is useful for testing models with different context window limitations.

run.sh

@@ -73,7 +73,8 @@ else
     echo ""
     echo "Примеры использования:"
     echo " * ./run.sh run -m second_constantine/t-lite-it-1.0:7b -b translation summarization"
-    echo " * ./run.sh run -m second_constantine/t-lite-it-1.0:7b --num-ctx 16000"
+    echo " * ./run.sh run -m second_constantine/t-lite-it-1.0:7b -u http://10.0.0.4:11434 -c 2048 -b translation summarization"
+    echo " * ./run.sh run -m translategemma:4b -u http://10.0.0.4:11434 -c 128000 -b summarization"
     echo " * ./run.sh gen"
     echo " * ./run.sh gen-mongo 507f1f77bcf86cd799439011"
     echo " * ./run.sh gen-mongo --id-file ids.txt"