chore: remove confused reaction on thread-build failure

The confused emoji reaction was confusing users when thread context
building failed. Remove the step entirely - failures are already
logged in the workflow run.

Author: derekmisler

.github/workflows/review-pr.yml

@@ -657,20 +657,3 @@ jobs:
           mistral-api-key: ${{ secrets.MISTRAL_API_KEY }}
           github-token: ${{ steps.app-token.outputs.token || github.token }}
           skip-auth: "true" # Org membership already verified above
-
-      - name: React on thread-build failure
-        if: >-
-          always() &&
-          steps.check.outputs.is_agent == 'true' &&
-          steps.auth.outputs.authorized == 'true' &&
-          steps.thread.outcome == 'failure'
-        continue-on-error: true
-        shell: bash
-        env:
-          GH_TOKEN: ${{ steps.app-token.outputs.token || github.token }}
-          REPO: ${{ github.repository }}
-          COMMENT_ID: ${{ github.event.comment.id }}
-        run: |
-          gh api "repos/$REPO/pulls/comments/$COMMENT_ID/reactions" \
-            -f content="confused" --silent || true
-          echo "😕 Thread context build failed — added confused reaction"