fix: Simplify benchmark CI job to avoid gh-pages requirement

Remove benchmark result storage action that required gh-pages branch.
Benchmarks now run as part of CI without storing historical data.

This fixes the CI failure without requiring GitHub Pages setup.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: richardwooding

.github/workflows/ci.yml

@@ -65,16 +65,4 @@ jobs:
       run: go mod download
 
     - name: Run benchmarks
-      run: go test -bench=. -benchmem -benchtime=1s -run=^$$ ./... | tee benchmark-results.txt
-
-    - name: Store benchmark result
-      uses: benchmark-action/github-action-benchmark@v1
-      with:
-        tool: 'go'
-        output-file-path: benchmark-results.txt
-        github-token: ${{ secrets.GITHUB_TOKEN }}
-        auto-push: false
-        comment-on-alert: true
-        alert-threshold: '150%'
-        fail-on-alert: false
-        summary-always: true
+      run: go test -bench=. -benchmem -benchtime=1s -run=^$$ ./...