fix(cpn): Application tab content disappearing when collapsing a section

PrefsAppPanel/PrefsProfilePanel/PrefsUpdatePanel wire every
AutoCollapsibleSection's animation-finished callback to
AbstractPanel::shrink(), which does adjustSize() followed by
resize(0, 0) to force a re-layout. That idiom is only safe for the
top-level QDialogs it was copied from elsewhere in Companion; these
panels are child widgets hosted in a QScrollArea, and forcing them to
(0, 0) can leave them stuck at zero size instead of being regrown by
the scroll area - blanking the whole tab, e.g. when collapsing "Radio
Profiles" on the Application tab while "General" is left expanded.

Give PrefsPanel its own non-destructive shrink() (updateGeometry())
that shadows AbstractPanel::shrink() for these scroll-area-hosted
panels.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MAYL7FYuZNTmb4sEaig3bN

companion/src/prefsedit/prefs_panel.cpp

@@ -59,6 +59,13 @@ void PrefsPanel::onRadioChanged(Firmware * firmware, bool deferUpdate)
     update();
 }
 
+void PrefsPanel::shrink()
+{
+  // resize(0,0) (AbstractPanel::shrink()) assumes a top-level widget; here the
+  // panel lives in a QScrollArea and can get stuck at zero size instead.
+  updateGeometry();
+}
+
 /*
     PrefsScrollArea
 */

companion/src/prefsedit/prefs_panel.h

@@ -61,6 +61,7 @@ class PrefsPanel : public AbstractPanel
 
     AutoLineEdit * newPathWidget(QWidget * parent);
     void setPathWidget(AutoLineEdit * wgt);
+    void shrink();
 
 };