fix: simplify code review prompt to let plugin auto-detect PR context

The previous prompt format passed the PR path as an argument which
caused gh CLI to interpret it as a branch name, failing with
"no pull requests found". Let the plugin resolve PR info from
the GitHub Actions context instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: senna-lang

.github/workflows/claude-code-review.yml

@@ -38,7 +38,7 @@ jobs:
           claude_code_oauth_token: ${{ secrets.CLAUDE_CODE_OAUTH_TOKEN }}
           plugin_marketplaces: 'https://github.com/anthropics/claude-code.git'
           plugins: 'code-review@claude-code-plugins'
-          prompt: '/code-review:code-review ${{ github.repository }}/pull/${{ github.event.pull_request.number }}'
+          prompt: '/code-review:code-review'
           allowed_bots: 'claude'
           show_full_output: true
           # See https://github.com/anthropics/claude-code-action/blob/main/docs/usage.md