Issue comment workflow: Claude runs but doesn't post comments to issues

## Description

When using claude-code-action with issue events (not PR events), Claude runs successfully and generates results, but comments are not posted back to the issue.

## Workflow Configuration

```yaml
name: claude-issue

on:
issues:
types: [opened, edited]
issue_comment:
types: [created, edited]

jobs:
claude-issue:
runs-on: ubuntu-latest
if: github.actor \!= 'github-actions[bot]' && github.actor \!= 'claude[bot]'
permissions:
contents: write
issues: write
pull-requests: write
id-token: write

steps:
- uses: actions/checkout@v4
- uses: anthropics/claude-code-action@v1
with:
claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
prompt: |
You are a feature assistant...
[detailed prompt here]
```

## Observed Behavior

1. Workflow triggers correctly on issue creation/comments
2. Claude runs and analyzes the codebase (visible in run logs)
3. Claude produces a `result` with analysis/recommendations
4. **Result is NOT posted as a comment on the issue**
5. Result only appears in the GitHub Actions run summary

## Expected Behavior

Claude's response should be automatically posted as a comment on the issue, similar to how it works for PR reviews.

## Logs

Run logs show:
- `Auto-detected mode: agent for event: issue_comment`
- Claude's result is captured in the output JSON
- No GitHub API calls to create comments visible

## Tested Configurations

Tried various configurations:
- With/without `trigger_phrase: ""`
- With/without `--allowedTools` restrictions
- With `@claude` mention in comment

All result in the same behavior: Claude runs but doesn't post comments.

## Environment

- claude-code-action version: v1 (latest)
- Runner: ubuntu-latest

## Questions

1. Is comment posting on issues supported, or only for PRs?
2. Is there a specific configuration needed to enable comment posting?
3. Should this be filed as a bug or feature request?