Adds client-side i18n support, language settings, translated UI copy, and locale parity coverage.
* fix: handle Pi compact slash command * fix: handle Pi compaction slash commands * fix: harden Pi compaction commands * fix: handle missing Pi autocompaction state --------- Co-authored-by: X <X@16x.org> Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>