fix(docker): tolerate malformed entrypoint port env

[yyswhsccc]

Problem

docker-entrypoint.py parsed PORT directly in the container startup path. A malformed deployment env value raises ValueError before the Docker entrypoint can start the RustChain dashboard/health endpoint.

Impact

A single bad PORT value can crash the Docker container at startup, making the dashboard and /health endpoint unavailable until the environment is corrected.

Fix

Add a small local _safe_int_env helper and use it for the entrypoint port. Valid numeric values are preserved, while malformed values fall back to the existing 8099 default.

Tests

• uv run --no-project --with pytest --with flask python -B -m pytest -q tests/test_docker_entrypoint_env.py -> 3 passed
• python3 -m py_compile docker-entrypoint.py tests/test_docker_entrypoint_env.py -> passed
• git diff --check -> passed

Boundaries

Related to the general bug bounty surface (#305). This PR does not change payout amounts, wallet crediting, admin secrets, or production wallet behavior.

wallet: RTC47bc28896a1a4bf240d1fd780f4559b242bcd945

[yyswhsccc]

@Scottcjn Please take a look when you have a chance. This is a small Docker startup hardening fix: malformed PORT now falls back to the existing default instead of crashing the container entrypoint before /health can serve.

Validation:

• uv run --no-project --with pytest --with flask python -B -m pytest -q tests/test_docker_entrypoint_env.py -> 3 passed
• python3 -m py_compile docker-entrypoint.py tests/test_docker_entrypoint_env.py -> passed
• git diff --check -> passed

[jaxint]

✅ Code reviewed - implementation verified.

[jaxint]

✅ Code reviewed - implementation verified. Good work on the changes.

[jaxint]

This PR looks good! Appreciate the contribution.

Reviewed for Bounty #71
Wallet: AhqbFaPBPLMMiaLDzA9WhQcyvv4hMxiteLhPk3NhG1iG

[jaxint]

✅ Code reviewed - implementation verified. Per bounty #71.