import: a .rsbank lands as a new bank, whole or not at all

Four collisions answered explicitly: ids reminted, names never overwritten,
content deduped before the write, bank name auto-suffixed. Degraded ledger
refuses before the picker.

src/shell/panel/panel_window.cpp

@@ -15,6 +15,7 @@
 
 #include "shell/panel/draw_kit.h"
 #include "shell/actions/ingest.h"
+#include "shell/actions/package_import_action.h"
 
 #ifdef _WIN32
 #include <windowsx.h>  // GET_X_LPARAM / GET_Y_LPARAM (SWELL supplies them on mac/linux)
@@ -40,12 +41,24 @@ PanelState g_panel;
 
 namespace {
 
+bool isPackagePath(const std::string& path) {
+    static const std::string kExt = ".rsbank";
+    if (path.size() <= kExt.size()) return false;
+    std::string tail = path.substr(path.size() - kExt.size());
+    for (char& c : tail)
+        if (c >= 'A' && c <= 'Z') c = static_cast<char>(c - 'A' + 'a');
+    return tail == kExt;
+}
+
 // DragQueryFile(hDrop, 0xFFFFFFFF, ...) returns the file count; each path is then
 // queried by index (length first, excludes NUL, then a sized buffer). DragFinish
-// always frees the shell-allocated drop buffer. Multi-file drop imports all into
-// the active bank (bank-fill only — no assignment to any live instance).
+// always frees the shell-allocated drop buffer. A .rsbank is a whole bank, not audio,
+// so it routes to the import verb (one new bank each); everything else keeps the
+// existing ingest route — multi-file drop imports all into the active bank (bank-fill
+// only, no assignment to any live instance).
 void handleDropFiles(HDROP hDrop) {
     std::vector<std::string> paths;
+    std::vector<std::string> packages;
     const UINT count = DragQueryFile(hDrop, 0xFFFFFFFF, nullptr, 0);
     paths.reserve(count);
     for (UINT i = 0; i < count; ++i) {
@@ -54,9 +67,14 @@ void handleDropFiles(HDROP hDrop) {
         std::vector<char> buf(static_cast<std::size_t>(len) + 1, '\0');
         DragQueryFile(hDrop, i, buf.data(), static_cast<UINT>(buf.size()));
         std::string p(buf.data());
-        if (!p.empty()) paths.push_back(std::move(p));
+        if (p.empty()) continue;
+        if (isPackagePath(p)) packages.push_back(std::move(p));
+        else paths.push_back(std::move(p));
     }
     DragFinish(hDrop);
+    if (g_panel.session)
+        for (const std::string& pkg : packages)
+            doImportBankPackageFile(*g_panel.session, pkg);
     if (!paths.empty()) ingestDroppedFiles(paths);
 }