feat: show run failure, cancel, and truncation reasons

[Navneethd8]

Summary

• Adds status_reason, status_detail, and list-level outcome fields to the frontend Run type and documents batchRunStatus for lightweight polling.
• Introduces runStatus.ts helpers and a RunStatusReason component for human-readable terminal explanations.
• Surfaces reasons in Recent runs, Live run monitor, Developer dashboard run lists, and Test bench results; episode rows now show terminal_info.reason (step limit, token budget, cancellation, etc.).

Pairs with swecc-core bench-api changes (status_reason / status_detail on runs and /v1/runs/status).

Test plan

• Submit a run that completes — no reason banner; scores still show
• Cancel an in-flight run — UI shows user_cancelled
• Fail a run (e.g. env down) — run row shows status_reason and episode-level detail
• Truncated episode — episode row shows step limit reason
• npm run lint && npm run build

Made with Cursor

[github-actions]

Marking as stale since there has been no activity for 30 days. Will close in 7 days if no activity.