feat(ui): rework work console — single Session tab, right-aligned header, turns x/y

- Merge "Actions" + "Session" into one state-aware Session tab: review controls
  on top, then merge/worktree management, then child outcomes — each gated on the
  current state, with an empty-state hint when there's nothing to manage. This is
  the home the real merge/diff work (task 09eb5d52) will slot into.
- Move the model · turns · diff info block to the right of the title bar.
- Show turns as current/max using the resolved turn budget (task → list → global).
- Output terminal now fills the console body cleanly: clip the console to its
  rounded corners and inset the embedded terminal instead of clipping its bottom.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

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

@@ -4,7 +4,7 @@
              xmlns:loc="using:ClaudeDo.Ui.Localization"
              x:Class="ClaudeDo.Ui.Views.Islands.SessionTerminalView"
              x:Name="Root">
-  <Border Classes="terminal" Margin="18,8,18,0">
+  <Border Classes="terminal" Margin="0">
     <DockPanel LastChildFill="True">
 
       <!-- ── Terminal header bar ── -->