feat(core): 模型选择框换 restraint chip 下拉 + worker 并发出图(修 -P solo 串行)

UI:脚本助手模型框从『原生 select + inline style』换成复用设计系统的 chip 下拉(向上展开,新增共享 .align-up 变体),去 inline、合规范。并发:本地 worker 从 -P solo(单任务串行=一次只生成一张)改 -P threads -c 4;生产 k8s worker --concurrency 2→4。基础资产/故事板/视频出图可并行。loading 动画基础设施(卡内+全局 spinner)已验证存在。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

k8s/core/worker-deployment.yaml

@@ -23,7 +23,7 @@ spec:
         # Celery worker connects to the external (Volcano managed) Redis broker
         # configured via the airshelf-core-env secret. Uses `args` (not `command`)
         # so the image ENTRYPOINT still runs but skips migrate/collectstatic ($1=celery).
-        args: ["celery", "-A", "airshelf.celery:app", "worker", "-l", "info", "--concurrency", "2"]
+        args: ["celery", "-A", "airshelf.celery:app", "worker", "-l", "info", "--concurrency", "4"]
         envFrom:
         - secretRef:
             name: airshelf-core-env