* feat(app): restore compact Changes diff controls
Keep the folder tree behind a view toggle while preserving the flat file list as the default.
Move secondary diff options into the overflow menu so the Changes toolbar stays compact.
* fix(app): mirror whitespace diff option copy
* fix(app): polish diff controls review follow-up
* fix(app): keep compact explorer mounted while open
* fix(app): share compact explorer host state
* fix(app): refresh diff row metrics after font changes
