Design status: clear the DoF line on leaving sketch mode, and wrap the HUD chip

Two independent leftovers, both in the same status area.

snaporca-752: the "N degrees of freedom" line described a sketch's constraint
state and stayed on screen after Confirm, Cancel and the Escape downgrade, in
Feature mode where it means nothing — visible in every Feature-mode screenshot of
the 2026-07-27 sweep. Cleared in set_ui_mode rather than at those three exits,
because that is the one place all of them pass through and a fourth exit added
later would otherwise reintroduce it. Constrain mode keeps the readout: that is
where the number is the whole point.

snaporca-8cc: moving the status out of the panel and into the viewport HUD
removed the clipping, but not the underlying problem. The chip is a top-level
popup that Fit()s to its text, so a long sentence grew past the right edge of the
canvas and hung over the window instead of being cut off inside it — the same
silent length limit wearing a different hat. The label now wraps to the room
actually available (canvas width minus the view-cube inset), which is what makes
the earlier promise that "a sentence can be a sentence" true at 1366 as well as
at 1920.

SetLabel + Wrap + Fit are now one function called from both the text change and
the placement. Wrap() rewrites the label it is handed, so it has to follow a
fresh SetLabel every time, and the placement path runs on resize — a chip wrapped
for the old width either overhangs a narrowed canvas or wastes a widened one.
The left inset is one constant now because the wrap width and the anchor have to
agree, or the chip wraps to a width it is not then given.

snaporca-752, snaporca-8cc. Reviewed and compiled (RC=0), not exercised.

src/slic3r/GUI/DesignPanel.cpp

@@ -3918,6 +3918,15 @@ void DesignPanel::set_ui_mode(UiMode m)
 {
     m_ui_mode = m;
     if (m != UiMode::Sketch) m_sketch_on.clear();   // no stale "on the picked face" on the next hint
+    // The DoF readout describes a SKETCH's constraint state, so it means nothing back in Feature
+    // mode — where it nonetheless stayed on screen after every Confirm, Cancel and Escape
+    // (snaporca-752). Cleared here rather than at those three exits because this is the one place
+    // all of them pass through, and a fourth exit added later would otherwise reintroduce it.
+    // Constrain mode keeps it: that is where the number is the whole point.
+    if (m == UiMode::Feature && m_dof_status != nullptr) {
+        m_dof_status->SetLabel(wxString());
+        m_dof_status->Show(false);
+    }
     wxSizer* s = m_toolbar->GetSizer();
     s->Show(m_tb_feature,   m == UiMode::Feature,   true);
     s->Show(m_tb_sketch,    m == UiMode::Sketch,    true);