fix(dev-lead): expose ACTION_TIMEOUT_SEC repo var in workflow env #294

Problem

The `fix-issue` path calls `run_writer`, which uses `ACTION_TIMEOUT_SEC` (default 600s/10 min) — not `DEEP_TIMEOUT_SEC`. PR #293 added `DEEP_TIMEOUT_SEC` but that only affects PR-review deep analysis, not the issue implementation path.

The result: gh-aw workflow authoring (issue #234, #233, etc.) still fails at exactly 10 minutes.

Fix

Add `ACTION_TIMEOUT_SEC` to the top-level `env:` block in `.github/workflows/dev-lead.yml`, immediately after the existing `DEEP_TIMEOUT_SEC` line:

```yaml
DEEP_TIMEOUT_SEC: ${{ vars.DEEP_TIMEOUT_SEC || '600' }}
ACTION_TIMEOUT_SEC: ${{ vars.ACTION_TIMEOUT_SEC || '600' }}
```

This is a one-line addition, same pattern as PR #293.

After merging

The repo variable `ACTION_TIMEOUT_SEC=1800` is already set. No further action needed — just merge this PR.