## Why
Completion timestamps always used a 12-hour clock, even when the host preferred 24-hour time.
## What changed
- Detect the clock preference from native settings on macOS and Windows, and from `LC_ALL`, `LC_TIME`, then `LANG` on Linux with glibc.
- Render completion times in the detected format, such as `14:32` instead of `2:32 PM`, for both live turns and restored history.
- Cache detection without changing the process locale, and retain 12-hour output when the preference cannot be determined. Recognize standard `C` and `POSIX` locales as 24-hour on Linux and Android.
## Testing
Add tests for locale precedence, unavailable locales, and clock pattern parsing, plus snapshot coverage for 24-hour timestamps with dates and line wrapping. Update completion timestamp normalization to handle both clock formats.
GitOrigin-RevId: eb338e67de627cbb992de16058884ece2b4b9ff7
Eric Traut
79ef00ded1