Sandbox override confirmation now reflects the save result

The sandbox limits what commands run by Claude Code can reach, and its "Configure overrides" dialog lets you change some of its settings. The confirmation message there now includes the result of saving those settings. Before, the same message was shown regardless.

Separately, when Claude Code reads git settings with a given set of environment variables (named values a program reads at start-up), it now runs git with only those variables instead of adding them to its own.