fix: change sync-branches permissions from read-all to contents: write

The sync-branches workflow performs git push to update autoloop/* branches,
but permissions: read-all only grants read-only access. With read-only
GITHUB_TOKEN permissions, pushes are rejected.

Update to contents: write which is the minimum required scope for git push.

Agent-Logs-Url: https://github.com/githubnext/autoloop/sessions/39a3c2d0-3885-4259-ad1e-9276a166556e

Co-authored-by: mrjf <180956+mrjf@users.noreply.github.com>

Author: Copilot

.github/workflows/sync-branches.lock.yml

@@ -9,7 +9,8 @@ on:
     branches: [main]  # ← update this if your default branch is not 'main'
   workflow_dispatch:
 
-permissions: read-all
+permissions:
+  contents: write
 
 timeout-minutes: 10