feat: add Claude PR Assistant workflow for direct PR improvements

- Create new workflow for PR comment-based Claude assistance
- Support multiple commands: implement, fix, improve, update, refactor, help
- Work directly on PR branches without creating new PRs
- Include comprehensive permission checks (bvdaakster only)
- Add detailed documentation and usage examples
- Support quality checks: build, typecheck, lint, test
- Include smart context awareness of PR changes

Features:
- Direct PR branch modification
- Multiple trigger commands for different types of assistance
- Comprehensive error handling and user feedback
- Quality assurance with automated checks
- Detailed commit messages with attribution

Commands:
- @claude implement - Add new functionality
- @claude fix - Fix bugs or errors
- @claude improve - Enhance existing code
- @claude update - Update to requirements
- @claude refactor - Restructure code
- @claude help - General assistance

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

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

.github/claude-config.json

@@ -10,6 +10,27 @@
     "codeReview": {
       "strategy": "privilegedUsers",
       "description": "Only bvdaakster can trigger Claude reviews"
+    },
+    "prAssistant": {
+      "strategy": "privilegedUsers",
+      "description": "Only bvdaakster can use Claude PR assistance"
+    }
+  },
+  "workflows": {
+    "issueImplementation": {
+      "file": "claude-implement-issue.yml",
+      "triggers": ["@claude implement", "@claude fix", "@claude create"],
+      "description": "Creates new branch and PR for issue implementation"
+    },
+    "codeReview": {
+      "file": "claude-code-review.yml",
+      "triggers": ["automatic on PR"],
+      "description": "Automatic code review for PRs from privileged users"
+    },
+    "prAssistant": {
+      "file": "claude-pr-assistant.yml",
+      "triggers": ["@claude implement", "@claude fix", "@claude improve", "@claude update", "@claude refactor", "@claude help"],
+      "description": "Assists with PR improvements directly on the PR branch"
     }
   },
   "strategies": {