Add missing hints for ConstrainRadiam tool

- Add hints entry for Sketcher_ConstrainRadiam in hints array
- ConstrainRadiam now shows 'pick circle or arc' hint like other radius/diameter tools
- Fixes part of issue #22282 - missing radius constraint hints

src/Mod/Sketcher/Gui/CommandConstraints.cpp

@@ -1230,6 +1230,10 @@ private:
             .selectionStep = 0,
             .hints = {{QObject::tr("%1 pick circle or arc"), {Gui::InputHint::UserInput::MouseLeft}}}},
 
+            {.commandName = "Sketcher_ConstrainRadiam",
+            .selectionStep = 0,
+            .hints = {{QObject::tr("%1 pick circle or arc"), {Gui::InputHint::UserInput::MouseLeft}}}},
+
             // Angle
             {.commandName = "Sketcher_ConstrainAngle",
             .selectionStep = 0,