Selection Pane: reorder by drag and drop, groups, Show/Hide All and Lock, as in PowerPoint (#133) (#332)

* #133: Selection pane engine: restack inside groups, Show/Hide All, Lock like PowerPoint

- arrange.bringForward/sendBackward/bringToFront/sendToBack and arrange.reorder work on a
  group's children, which stay in their group (as PowerPoint's pane arrows and drag do);
  steps that change nothing leave no undo step.
- selection.select (pane click: Ctrl toggles, children and top-level objects don't mix,
  picking a hidden object shows it), selection.showAll (everything, children too) and
  selection.hideAll (top level).
- shape.lock cascades through groups; locked objects can be selected, formatted and typed
  in, but not moved, sized, rotated, flipped, reshaped or cropped (commands and canvas).
- PPTX: Lock reads and writes PowerPoint's full locking attribute set per element kind
  (observed by saving locked objects from PowerPoint); partial locks aren't Lock.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

* Front-most first with groups folding; drag a row to restack among its siblings (accent
insertion line); Bring Forward / Send Backward arrows; Show All / Hide All; per-row eye and
padlock; double-click or F2 renames in place; Ctrl+click toggles, Shift+click selects a run;
arrows, Home, End and Esc in the list; right-click menu. Lock/Unlock on the canvas menu,
greyed handles on locked objects. egui_kittest tests drive the pane.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/ui-parity.md

@@ -29,7 +29,7 @@ AGENTS.md §2). Dimension score: **~60% ready** (estimated), **30–50 h** to pa
 |---|---|---|
 | Format Shape / Picture / Text pane (Fill & Line, Effects, Size & Properties, Picture, Text Box) | full | partial: fill, gradient editor, line, some effects, size; no 3-D, thin picture/texture options |
 | Format Background pane | yes | yes |
-| Selection Pane | yes | yes |
+| Selection Pane | front-most first, groups fold, drag to restack, Bring Forward / Send Backward arrows, Show All / Hide All, eye, padlock (Lock), rename in place | same: drag restacks among siblings (a child stays in its group), Ctrl+click toggles, Shift+click selects a run, arrows / Home / End / F2 / Esc in the list, right-click menu |
 | Animation Pane | list + advanced timeline | list, reorder, timing; no timeline |
 | Comments pane (threads) | yes | yes |
 | Design Ideas (Designer) | yes (cloud) | no |
@@ -89,4 +89,6 @@ imitate Microsoft's. No pixel comparison against PowerPoint screenshots has been
 | Date | Change | Summary |
 |---|---|---|
 | 2026-10-12 | minor | Off-slide objects drawn and editable around the slide in Normal view (#270) |
+
+| 2026-10-12 | minor | Selection Pane matched to PowerPoint (#133): drag and drop, arrows, groups, eye, Lock |
 | 2026-10-10 | major | Created: shell, panes and dialogs, direct manipulation, shortcuts and visual fidelity against PowerPoint 16.113 |