Ψ-W1-T4 remediation: gate silent arrange drops, pin surface totality, hedge unverified SDK claims, close comment/exception-safety minors

src/shell/panel/panel_state.h

@@ -134,6 +134,7 @@ using ui::hitTestSlot;
 using ui::hitTestTabStrip;
 using ui::menuButtonReserve;
 using ui::navigate;
+using ui::needsSurfaceProbe;
 using ui::roleColor;
 using ui::stripActionPrefix;
 using ui::tagButtonEnabled;
@@ -320,10 +321,9 @@ struct PanelState {
     CardGesture cardGesture = CardGesture::None;
     int         dragTargetSlot = -1;
 
-    // NO out-of-client drop-target state is kept here on purpose. The drag-out class and its
-    // track are re-resolved from the live pointer on every move and again at the release point,
-    // which is what makes a class transition reversible and one unresolvable evaluation
-    // harmless to the next. Do not reintroduce a remembered target or a "blocked" latch.
+    // NO out-of-client drop-target state is kept here on purpose (core/ui/CLAUDE.md: "the
+    // drag-out law is per-move and stateless"). Do not reintroduce a remembered target or a
+    // "blocked" latch.
 
     // Authoritative tail setting lives in ReaSamplerSession, not here; panel reads it for
     // drawing and mutates via footer click / scroll-wheel. bankPanelTailSetting is the