🤖 Implement Gemini PR Pre-review Reflex

This PR adds a new reflex action to the Gemini CLI Bot that automatically provides high-level pre-reviews for new pull requests.

### Changes:
- Created `tools/gemini-cli-bot/reflexes/scripts/pr_pre_review.ts`: A reflex script that uses Gemini to evaluate PRs based on quality, roadmap alignment, "obvious wins," and repository best practices.
- Updated `.github/workflows/gemini-cli-bot-pulse.yml`: Added `GEMINI_API_KEY` and ensure the Gemini CLI is bundled before running reflex actions.

### Impact:
- **Time to First Response**: Will decrease as the bot provides initial feedback within 30 minutes of PR submission.
- **Maintainer Productivity**: High-level assessments and roadmap alignment checks will help maintainers prioritize reviews.
- **Contributor Experience**: Immediate feedback on best practices and roadmap alignment.

This addresses the request in issue #26471.

.github/workflows/gemini-cli-bot-pulse.yml

@@ -34,9 +34,14 @@ jobs:
       - name: 'Install dependencies'
         run: 'npm ci'
 
+      - name: 'Build Gemini CLI'
+        run: 'npm run bundle'
+
       - name: 'Run Reflex Processes'
         env:
           GITHUB_TOKEN: '${{ secrets.GITHUB_TOKEN }}'
+          GEMINI_API_KEY: '${{ secrets.GEMINI_API_KEY }}'
+          GEMINI_MODEL: 'gemini-3-flash-preview'
         run: |
           if [ -d "tools/gemini-cli-bot/reflexes/scripts" ] && [ "$(ls -A tools/gemini-cli-bot/reflexes/scripts)" ]; then
             for script in tools/gemini-cli-bot/reflexes/scripts/*.ts; do