Merge pull request #414 from jerry609/test/milestone-v1.2

fix: resolve preview build and codeql issues

merge: resolve dev conflicts in layout shell

fix: address sonar security gate regressions

fix: resolve studio sonar quality issues

fix: stabilize signals hydration and flatten queue layout

feat: add signals workspace and daily brief settings

feat: improve dashboard empty states

refactor: remove standalone workflows surface

feat: streamline studio skill launch flow

feat: align studio skills with agent skill directories

feat: refine studio chat and monitor workflow

feat: sync login page with dev auth ui

feat: finalize studio chat density

feat: tighten studio chat surfaces