Feature request: Claude should search for duplicate issues before creating new ones

Description

When asked to file a GitHub issue, Claude should automatically search for existing similar issues before creating a new one. Currently, Claude will create issues without checking, which can lead to duplicates.

Current Behavior

When a user asks Claude to file an issue:

1. Claude creates the issue immediately with gh issue create
2. No duplicate check is performed
3. User may end up with a duplicate issue

Expected Behavior

When a user asks Claude to file an issue:

1. Claude searches for existing issues with relevant keywords using gh search issues
2. Reviews any similar-looking issues
3. If a duplicate exists, informs the user and offers to comment on the existing issue instead
4. Only creates a new issue if no duplicates are found

Example Workflow

# Step 1: Search with multiple keyword combinations
gh search issues --repo owner/repo "settings shadow" --limit 10
gh search issues --repo owner/repo "permissions merge" --limit 10

# Step 2: Review similar issues
gh issue view 12345 --repo owner/repo

# Step 3: Either comment on existing or create new
gh issue comment 12345 --repo owner/repo --body "..."
# OR
gh issue create --repo owner/repo --title "..." --body "..."

Motivation

This just happened in a session where Claude filed issue #20218, which turned out to be a duplicate of #17017 and #19487. The duplicate could have been avoided with a simple search first.

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This issue was written by Claude at the request of a user who experienced this behavior.