feat(ui): highlight user chat messages + opt-in interrupt (stop) button

LogKindForegroundConverter drives the log message foreground via a local
binding (beats the dim local value), so user messages render in the accent
color instead of vanishing into the transcript. Adds a small stop (Icon.Stop)
button next to Send in both composers (SessionTerminalView + WorkConsole) wired
to InterruptInteractiveCommand → InterruptInteractiveSessionAsync. Adds
session.composer.interrupt (en/de).

src/ClaudeDo.Ui/Views/MissionControl/MonitorPaneView.axaml

@@ -111,6 +111,7 @@
           IsComposerVisible="{Binding IsInteractiveLive}"
           ComposerText="{Binding ComposerDraft, Mode=TwoWay}"
           SubmitCommand="{Binding SubmitComposerCommand}"
+          InterruptCommand="{Binding InterruptInteractiveCommand}"
           ComposerPlaceholder="{loc:Tr session.composer.placeholder}" />
 
     </DockPanel>