Q-W2 review follow-ups: anon-namespace TU-private panel helpers, fix stale bank_panel.cpp comments, correct shim-transitivity claim

Wraps ~50 file-local helpers across all eight panel TUs in namespace{} (dissolves the menuAppend default-arg ODR trap); zero behavior change, 60/60 green.

src/shell/panel/panel_drag.cpp

@@ -30,6 +30,8 @@ namespace reasampler::panel {
 
 constexpr int kDragThreshold = 5;  // px the pointer must move to begin a drag
 
+namespace {
+
 // Resolves the drop target under client (x, y) during a drag, updating dropKind /
 // dropBankId. A drop onto the pool region -> the pool; onto a named tab -> that bank;
 // anywhere else -> none.
@@ -234,6 +236,8 @@ void updateHover(int x, int y) {
     }
 }
 
+}  // namespace
+
 // Applies the tooltip hover-delay: if a tooltip-bearing element has been hovered past
 // kTooltipDelayMs and the tooltip is not yet shown, latch it and repaint once. Driven from the
 // OnTimer poll (bankPanelRefresh) so the tooltip appears after a rest with no dedicated timer;
@@ -365,6 +369,8 @@ void onMouseMove(int x, int y) {
 // batched undo point + saves). A no-op reorder (already at the target, model returns false)
 // opens no undo point. Selection reasons over slot order, so it is cleared after — the
 // fingerprint pass rebuilds it against the new order.
+namespace {
+
 void doReorderDrop(const std::string& id, const std::string& bankId, int targetSlot) {
     if (!book() || id.empty() || bankId.empty() || targetSlot < 0) return;
     if (!book()->reorderSample(id, bankId, targetSlot)) return;  // rejected/no-op: no undo point
@@ -386,6 +392,8 @@ void doReplaceDrop(const std::string& newId, const std::string& oldId,
     invalidatePanel();
 }
 
+}  // namespace
+
 // Clears all drag-state fields to their resting values. Called from every exit path
 // (button-up, WM_CAPTURECHANGED, WM_DESTROY, closePanel) so the set of cleared fields
 // stays consistent across all four sites.