fix(ci): remove errant space in github.sha template expression

Space in `github.sha ::7` caused workflow validation to fail on push
events (0s run, no jobs). Fixes the template syntax so the SHA
subexpression is `github.sha::7`.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -210,7 +210,7 @@ jobs:
 
       - name: Deploy to groombook-dev
         env:
-          TAG: pr-${{ github.event.pull_request.number }}-${{ github.sha ::7}}
+          TAG: pr-${{ github.event.pull_request.number }}-${{ github.sha::7}}
           PR_NUM: ${{ github.event.pull_request.number }}
         run: |
           echo "Deploying images tagged $TAG to groombook-dev..."