fix(ui): wire details-island buttons and drop dead handlers

- Bind star button to ToggleStarCommand; wrap header and subtask
  done-check ellipses in buttons (ToggleDone / ToggleSubtaskDone).
- Wire AgentStrip copy-path button to clipboard handler.
- Remove dead Notes/PromptInput/ApproveMerge/ShowWorktreeModal code
  with no UI bindings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml

@@ -81,6 +81,7 @@
         <Button Grid.Column="2"
                 Classes="icon-btn"
                 ToolTip.Tip="Copy path"
+                Click="OnCopyWorktreePathClick"
                 VerticalAlignment="Center">
           <PathIcon Data="{StaticResource Icon.Copy}" Width="11" Height="11"/>
         </Button>