v1.91.5.0 feat: balanced free-suite shards, test:ubicloud, and faster PR eval lane (#2989)

* v1.91.5.0 feat: balanced free-suite shards, 16-way Linux runs, and bun run test:ubicloud

* chore: regenerate agents digest for v1.91.5.0

* ci: serial flaky retry and flake ledger for the Windows free lane

* ci: cancel superseded eval runs; relax LLM-judge clarity bar to 3

.github/workflows/quality-gate.yml

@@ -93,3 +93,6 @@ jobs:
           scripts/build-app.sh
           scripts/write-version-files.sh
           browse/scripts/build-node-server.sh
+          scripts/ubicloud/ubi-runner.sh
+          scripts/ubicloud/setup-free-suite.sh
+          scripts/ubicloud/test-free.sh