feat: enhance assistant to implement PR changes using Auggie SDK

Major enhancements:
- Add Auggie SDK integration to implement changes based on comments
- Gather comprehensive PR context (diff, files, comments, metadata)
- Automatically commit and push changes to PR branch
- Add success/failure comments to PR
- Configure git with GitHub Actions bot credentials
- Handle both issue_comment and pull_request_review_comment events

Dependencies:
- Add @augmentcode/auggie-sdk for AI-powered code changes
- Add @actions/exec for git operations

The action now:
1. Adds eyes reaction to show processing
2. Gathers PR context and comment thread
3. Invokes Auggie with full context
4. Commits and pushes implemented changes
5. Posts result comment to PR

Author: Tulga Tsogtgerel

assistant/action.yml

@@ -1,9 +1,9 @@
-name: "Comment Reaction"
-description: "React to GitHub comments with emoji reactions"
+name: "PR Assistant"
+description: "AI-powered PR assistant that implements changes based on comments using Auggie SDK"
 author: "Augment Code"
 branding:
-  icon: "eye"
-  color: "blue"
+  icon: "zap"
+  color: "purple"
 
 inputs:
   github_token:
@@ -42,7 +42,7 @@ runs:
       run: npm install --production
       shell: bash
       working-directory: ${{ github.action_path }}
-    - name: React to Comment
+    - name: Run PR Assistant
       id: react
       run: npx tsx ${{ github.action_path }}/src/index.ts
       shell: bash