ci: auto-resolve merge conflicts in beta sync using opencode

When merging PRs into the beta branch, the sync script now attempts to automatically resolve merge conflicts using opencode before failing. This reduces manual intervention needed for beta releases when multiple PRs have overlapping changes.

.github/workflows/beta.yml

@@ -27,7 +27,11 @@ jobs:
           opencode-app-id: ${{ vars.OPENCODE_APP_ID }}
           opencode-app-secret: ${{ secrets.OPENCODE_APP_SECRET }}
 
+      - name: Install OpenCode
+        run: bun i -g opencode-ai
+
       - name: Sync beta branch
         env:
           GH_TOKEN: ${{ steps.setup-git-committer.outputs.token }}
+          OPENCODE_API_KEY: ${{ secrets.OPENCODE_API_KEY }}
         run: bun script/beta.ts