Fix CI: restrict build to main branch, mark claude-review as non-blocking

- build-index.yml: add branches: [main] so the deploy-pages step doesn't
  fail when run from feature branches (deploy-pages only works from the
  pages environment, which requires the default branch)
- claude-code-review.yml: add continue-on-error: true until the Claude
  Code GitHub App is installed on this repository

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

Author: greynewell

.github/workflows/build-index.yml

@@ -2,6 +2,7 @@ name: Build Index
 
 on:
   push:
+    branches: [main]
     paths: [repos.yaml, generate-index.go, go.mod, go.sum, .github/workflows/build-index.yml]
   workflow_dispatch:
 

.github/workflows/claude-code-review.yml

@@ -7,6 +7,7 @@ on:
 jobs:
   claude-review:
     runs-on: ubuntu-latest
+    continue-on-error: true
     permissions:
       contents: read
       pull-requests: write