Add eyeball emoji acknowledgment to Claude PR review workflow

## Feature Request
Add an immediate visual acknowledgment when Claude is mentioned for PR reviews by having the workflow add an 👁️ emoji reaction.

## Current Behavior
When someone comments `@claude review this please`, the workflow triggers but there's no immediate feedback that Claude has seen the request.

## Proposed Enhancement
Add a step to the Claude PR review workflow that:
1. Detects when `@claude` is mentioned in a comment
2. Immediately adds an 👁️ (eyes) emoji reaction to the comment
3. Then proceeds with the actual review

## Implementation Example
```yaml
- name: Acknowledge review request
uses: actions/github-script@v7
with:
github-token: ${{ secrets.GITHUB_TOKEN }}
script: |
// Add eyeball reaction to show Claude saw the request
await github.rest.reactions.createForIssueComment({
owner: context.repo.owner,
repo: context.repo.repo,
comment_id: context.payload.comment.id,
content: 'eyes'
});
```

## Benefits
- **Immediate feedback**: Users know their request was received
- **Subtle acknowledgment**: Non-intrusive visual indicator
- **Better UX**: No wondering if the workflow triggered
- **Professional touch**: Shows the system is responsive

## Technical Notes
- Should work for both issue comments and PR review comments
- The emoji reaction happens before the actual review starts
- If the review fails, the emoji still shows the request was seen

Principle: developer-experience

Locate the Claude PR review workflow and inspect how it handles issue comments and PR review comments. Add the acknowledgment before the review begins, covering both comment types, and verify that the eyes reaction appears even when the review later fails.

Written by the indexing model from the issue text.