fix: remove --max-turns CLI arg from entrypoint

[dsiddharth2]

Summary

• Removed --max-turns CLI argument from entrypoint.sh since run_agent.py doesn't accept it
• MAX_TURNS env var is already picked up by config.py → batch_max_turns (default: 15), so no CLI passthrough is needed
• This was causing Docker container to fail with unrecognized arguments: --max-turns 40

Test plan

• Build Docker image and run against a PR to verify no argument errors
• Confirm MAX_TURNS env var still works when explicitly set