Add Bomberland arena

[Muhtasham]

Summary

Adds a Bomberland arena to CodeClash as a separate game adapter.

Bomberland is a Bomberman-style multi-agent grid arena based on Coder One's Bomberland competition. Players submit bomberland_agent.py with next_actions(game_state), controlling multiple units that move, place bombs, destroy blocks, damage opponents, and score across deterministic seeded simulations.

What changed

• Added BomberlandArena and registered it in the arena registry.
• Added a codeclash/bomberland Docker image that pins the upstream CoderOneHQ/bomberland repo for provenance at /opt/bomberland.
• Added a compact CodeClash-native Python runtime instead of requiring the upstream TypeScript websocket/docker-compose stack inside the arena container.
• Added a starter bomberland_agent.py, runtime README, public docs page, and dummy smoke config.
• Added unit coverage for validation, result parsing, command construction, registration, runtime timeouts, sibling imports, malformed actions, and config constraints.

Runtime contract

• Exactly two players per tournament.
• sims_per_round must be even so both players receive paired starting sides.
• validation_timeout bounds validation-time import/probe execution.
• agent_timeout bounds each runtime agent call in a child process, so hanging submitted code is scored as an agent error instead of hanging the round.
• Result files use average_scores, total_scores, sims, and per-simulation details JSON strings.

Notes

• Issue Add Pommerman as a game #8 tracks Pommerman. This PR adds Bomberland, which is related in game style but is not the same project, so it intentionally does not close Add Pommerman as a game #8.
• The runtime keeps the submission interface close to the upstream starter-kit shape where practical: connection.agent_id, agents[player].unit_ids, unit_state, entities, world, and tick.

Verification

• uv run ruff check codeclash/arenas/bomberland tests/arenas/test_bomberland.py codeclash/arenas/__init__.py
• uv run pytest tests/arenas/test_bomberland.py
• uv run python codeclash/arenas/bomberland/runtime/run_bomberland.py --sims 2 --ticks 40 --width 11 --height 11 --unit-count 3 --agent-timeout 0.25 --output /tmp/.../results.json --agent alpha=/tmp/.../alpha/bomberland_agent.py --agent beta=/tmp/.../beta/bomberland_agent.py
• docker image rm codeclash/bomberland >/dev/null 2>&1 || true; uv run python main.py configs/examples/Bomberland__dummy__r1__s2.yaml -o /tmp/codeclash-bomberland-smoke-1777983276
• uv run pytest tests/arenas
• uv run mkdocs build
• uv run pre-commit run --all-files
• uv run pytest

2026-06-24 refresh after mini-SWE-agent v2 merge

• Rebasing onto main after Migrate to mini-SWE-agent v2 #109 completed cleanly.
• Added reviewer-facing smoke-check docs with exact command, expected output shape, score fields, and metadata inspection command.
• uv run pytest -q tests/arenas/test_bomberland.py -> 14 passed.
• uv run pre-commit run --files docs/reference/arenas/bomberland.md codeclash/arenas/bomberland/runtime/README.md -> passed.
• OpenAI-backed mini-SWE-agent v2 smoke: one openai/gpt-4.1-mini player vs dummy, 1 round, 2 Bomberland sims, Docker runtime. Both pre-edit and post-edit Bomberland rounds completed with zero agent errors and scores of 220.0 for both players.
• GPT-5.5-backed mini-SWE-agent v2 smoke: one openai/gpt-5.5 player vs dummy, 1 round, 2 Bomberland sims, Docker runtime. The pre-edit round tied at 220.0 / 220.0; GPT-5.5 edited the bot; the post-edit round validated and scored 445.0 / 220.0 for gpt55_smoke, with no invalid submissions.
• CI after the refresh: markdown link check, pre-commit, and pytest passed before the latest docs-only commit; checks are rerunning for the docs update.