feat(interactive): host task-based ConPTY sessions in Command Center

Adds an 'Open ConPTY session' entry that fetches a task's launch spec and hosts
an embedded ConPTY terminal as a Mission Control pane, coexisting with the
streamed-log monitor panes (streaming stack untouched). Introduces IMissionControlPane
+ ConPtyPaneViewModel, a non-destructive Panes mirror (Monitors prefix + ConPtySessions
suffix) so unrelated monitor churn never tears down a live terminal, and a grid<->tabs
layout toggle. Launch failures surface via the footer error strip.

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

@@ -51,6 +51,8 @@
             <Separator/>
             <MenuItem Header="{loc:Tr tasks.ctxRunInteractively}"
                       Click="OnRunInteractivelyClick"/>
+            <MenuItem Header="{loc:Tr tasks.ctxOpenConPtySession}"
+                      Click="OnOpenConPtySessionClick"/>
             <MenuItem Header="{loc:Tr tasks.ctxPickUpInTerminal}"
                       Click="OnPickUpInTerminalClick"
                       IsVisible="{Binding CanPickUpInTerminal}"/>