feat: Complete GH-43 - Benchmark CI Workflow Integration (Refs #43)

Verified benchmark.yml workflow is complete and functional:
- Manual trigger (workflow_dispatch) with optional reason
- PR trigger for performance-sensitive file changes
- Weekly scheduled runs (Sunday 2 AM UTC)
- Artifact uploads (criterion results: 90-day, output: 30-day)
- PR comments with benchmark summaries

Workflow actively running on recent Dependabot PRs.

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

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

Author: noahgift

docs/roadmaps/roadmap.yaml

@@ -705,11 +705,11 @@ roadmap:
   github_issue: null
   item_type: task
   title: 'New task: GH-43'
-  status: inprogress
+  status: completed
   priority: medium
   assigned_to: null
   created: 2025-11-21T17:50:56.372225985+00:00
-  updated: 2025-11-21T17:50:56.372225985+00:00
+  updated: 2025-11-21T22:57:34.454368119+00:00
   spec: null
   acceptance_criteria: []
   phases: []