Rounded Rectangle sketch tool (#891) (#948)

* Rounded Rectangle sketch tool (#891)

A new SKETCH > CREATE command, sketch.rectangle.rounded, in the Rectangle
family: two opposite corners and a corner radius make a 2-point rectangle
whose four corners are filleted alike, as one undo step. The radius is one
parameter (one radius dimension, the other arcs equal to it), so changing it
changes all four corners. While drawing, Width, Height and Radius boxes take
typed values; typed width and height dimension the overall size between
opposite sides. Without a typed radius the corners get a fifth of the shorter
side.

Fixes #891

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Rounded Rectangle in the Simplified Chinese catalog

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

docs/i18n_catalog_ja.md

@@ -1,4 +1,4 @@
-# SolidCraft 英語・日本語 ローカライズ対照リスト (全 846 件)
+# SolidCraft 英語・日本語 ローカライズ対照リスト (全 847 件)
 
 | 英語 (English) | 日本語 (Japanese) | キー名 (Key) |
 | :--- | :--- | :--- |
@@ -670,6 +670,7 @@
 | Rim Edge | リムエッジ | `Rim Edge` |
 | Roll History Marker | 履歴マーカーを移動 | `cmd.timeline_roll_to` |
 | Roll History Marker Here | 履歴マーカーをここに移動 | `Roll History Marker Here` |
+| Rounded Rectangle | 角丸長方形 | `cmd.sketch_rectangle_rounded` |
 | Rule | ルール | `Rule` |
 | Save | 保存 | `ui.save` |
 | Save As | 名前を付けて保存 | `ui.save_as` |