release: v1.0.3

Bump version, update CHANGELOG, and retake README screenshots
(Jobs, History, Settings) to match the current GUI.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/version.go

@@ -3,4 +3,4 @@ package app
 // Version is the application version shown in the GUI and used by build
 // scripts in artifact names. It is a var rather than a const so release builds
 // can override it with Go ldflags when CI tags a build.
-var Version = "1.0.2"
+var Version = "1.0.3"