R2R was the only legacy plugin still keeping the solution-level build red
(27 errors against the Avalonia tree). Port mirrors the four-corner
substitution used for the rest of the rewrite:
Assisted-by: Claude:claude-opus-4-7:Claude Code
Replaces the WPF modal Options dialog with a Dock document tab — opens via
View → Options at the same MenuOrder=999 mount point, hosts the same three
panels (Decompiler / Display / Misc), and uses the same SettingsSnapshot
commit pattern so closing the tab without Apply discards in-flight edits.
Re-invoking View → Options while one's open just focuses the existing tab.
Assisted-by: Claude:claude-opus-4-7:Claude Code
Replaces the temporary 3-column Grid placeholder in MainWindow with a
Dock.Avalonia DockControl driven by an ILSpyDockFactory and orchestrated
by a [Shared] DockWorkspace exported via MEF.
Assisted-by: Claude:claude-opus-4-7:Claude Code
Lifted out of "Assembly tree pane scaffolding" so the toolbar control
exists at the point MainWindow.axaml references it. The control body
is empty for now; later commits flesh it out with the actual buttons.