Ψ-W1-T2 review remediation: solo restore drops on visible-in-target, not parked; N-mode segments read dead when unroutable

Fixes a hidden-parent solo replay that could silence the mix. Also closes the N-mode segment silent no-op, amends the invariant comment, trims view.cpp under 600 lines, hedges two SDK inferences, drops a dead null-check.

src/shell/panel/panel_state.h

@@ -292,10 +292,10 @@ struct PanelState {
     unsigned int hoverSinceTick = 0;
     bool tooltipShown = false;
 
-    // Polled on the OnTimer tick (REAPER exposes no transport-change callback): a mode
-    // switch is refused while the transport runs, so the footer's [Arrange|Design]
-    // segments paint disabled. Cached rather than read per paint AND per click so the
-    // pixel the user saw and the click they made cannot disagree within a tick.
+    // Polled on the OnTimer tick (REAPER exposes no transport-change callback). Feeds
+    // modeSegmentEnabled (core/ui/footer_bar.h). Cached rather than read per paint AND
+    // per click so the pixel the user saw and the click they made cannot disagree
+    // within a tick.
     bool modeSwitchBlocked = false;
 
     BankPanelFullHeight fullHeight = BankPanelFullHeight::Split;
@@ -485,6 +485,9 @@ void startAudition(int idx);
 // panel_input.cpp — click/wheel/key routing, accelerator, new-content detection,
 // and the session-tail read/mutate helpers.
 TailSetting currentTail();
+// The registered activate action behind a footer mode segment, or 0 if unroutable.
+// Shared with panel_render.cpp so paint and click resolve the same id.
+int modeActivateCommandId(const std::string& modeId);
 void handleClick(int x, int y);
 bool handleWheel(int x, int y, int delta);
 void registerAccel();