CI: run the e2e job only after the checks pass

A PR that's already red doesn't spend ~25 minutes of the RTX 4090.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

.gitea/workflows/ci.yml

@@ -61,8 +61,10 @@ jobs:
     # the RTX 4090 busy for ~25 minutes. On PRs only, as its own job so the
     # checks above report first; a newer push to the same PR cancels the
     # run it supersedes. Locally, run only what you're writing (-k) or
-    # diagnosing (--lf).
+    # diagnosing (--lf). Only after the checks pass: a PR that's red already
+    # doesn't spend the GPU.
     if: github.event_name != 'push'
+    needs: checks
     runs-on: ubuntu-latest
     timeout-minutes: 90
     concurrency: