Allow container stop and restart in container-runtime profile

[axellpadilla]

Summary

The container-runtime profile claims to support DockerRunLauncher lifecycle calls, but it denied POST /containers/{id}/stop — the exact endpoint DockerRunLauncher.terminate() uses to cancel runs. Since deny-overrides blocks any allowlist override while the profile is active, run termination failed with 403 and runs hung in CANCELING with worker containers still running.

Closes #20.

Changes

• src/security.rs: grant POST /containers/{id}/stop and POST /containers/{id}/restart in the container-runtime profile by adding them to RUNTIME_ENDPOINTS and removing them from the profile's retained write-denial list.
• Tests: assert stop and restart are allowed in container_runtime_profile_allows_launcher_workflow, and container_runtime_profile_keeps_destructive_ops_denied confirms kill, pause, unpause, rename, update, resize, attach, and commit stay denied.
• README.md: document that graceful termination and restart are included; CHANGELOG.md: [Unreleased] Fixed entry.

Design decision

Only stop and restart are granted. DockerRunLauncher in dagster-docker never calls kill/pause, so those remain denied (least privilege, no behavior loss). Stop is the graceful, reversible SIGTERM path; restart is compositionally stop+start, so denying it once stop and start are both granted would be a ceremonial boundary with no security value — the profile already granted the irreversible DELETE /containers/{id}, so this closes the lifecycle gap rather than widening it.

Validation

• cargo fmt --all --check — pass
• cargo clippy --all-targets -- -D warnings — clean
• cargo test --locked — 88 passed / 0 failed