Reuse grouped selector for dashboard library scope - #33

Summary

• replace the dashboard's native library select with the same searchable grouped popup used by Item Library and Home Library fields
• keep All library systems, whole-system scopes, and individual branches in one reusable selector
• add dashboard fiscal-period support to the CLI
• update browser coverage for the shared selector and mobile popup scoping

Verification

• 280 unit tests pass
• ESLint passes for the changed application modules
• live API system/fiscal request verified after request-boundary hotfix
• browser smoke reached and passed the dashboard selector flow; a later pre-existing dark-theme surface assertion remains intermittent