Feature/local execution backend

[pelin17]

Summary

Adds a new local execution backend for rapid local development. When developing or debugging tools, re-installing all packages from scratch on every submission is slow. The local backend skips provisioning and installation entirely, running benchmarks directly on the backend machine against a pre-installed local tool directory.

Changes

• comp_eval_platform/compute/local.py — new LocalBackend class
• comp_eval_platform/compute/base.py — registered LocalBackend in the backend registry
• comp_eval_platform/compute/shell.py — node_exec and _ping route to local subprocess when IP is 127.0.0.1
• comp_eval_platform/core/management/commands/init_settings.py — local added as a valid execution_backend value
• comp_eval_platform/settings.py — added LOCAL_TOOL_DIR and LOCAL_BENCHMARK_DIR config knobs

Behavior

Step	local_docker / aws	local
Assign Worker	Docker/EC2 provision (~1-2 min)	Instant (0s)
Install Tool	git clone + install_tool.sh	Skipped (0s)
Run Benchmark	Via SSH to worker node	Direct subprocess on backend

Configuration

EXECUTION_BACKEND=local
LOCAL_TOOL_DIR=/path/to/tool        # directory with install_tool.sh, run_instance.sh etc.
LOCAL_BENCHMARK_DIR=/path/to/benchmarks_repo

Proof of Local Backend Execution

As shown below, the Install Toolkit steps are skipped (0s) when using the new local backend.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[toladnertum]

Looks very good, thanks for the detailed description!