Continuity for Windows v0.4.2

External-change handling: reopening or reloading a file changed on disk now shows current content (silently if you have no unsaved edits, with a prompt if you do). Saving no longer silently overwrites a file changed on disk behind your back — you get a Reload / Keep mine / Show diff banner with clickable buttons and a real line-by-line diff. Reopening an already-open file focuses its existing tab instead of opening a duplicate window. Every theme now has its own distinct text-selection color and a subtler current-line highlight (all 17 themes).