Redo connection manager: Stacks, More options, drag & drop, WinSCP import

Folders become Stacks (connections.json v2, no v1 migration): collapsible
stack-first list, open-stack-in-tabs (first reuses a pristine tab), drag
connections between stacks. More... reveals a per-connection Local
directory applied to the other panel when local and untouched. Import
reads a WinSCP.ini export incl. deobfuscated passwords.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ui/src/app/file-panel/file-panel.html

@@ -95,10 +95,10 @@
         }
       </button>
 
-      @if (connections.grouped().root.length || connections.grouped().folders.length) {
+      @if (connections.grouped().loose.length || connections.grouped().stacks.length) {
         <div class="my-1 border-t border-border"></div>
       }
-      @for (connection of connections.grouped().root; track connection.id) {
+      @for (connection of connections.grouped().loose; track connection.id) {
         <button
           (click)="pickConnection(connection)"
           class="flex w-full items-center gap-2 px-3 py-1.5 text-left text-(length:--path-font) hover:bg-accent"
@@ -107,9 +107,9 @@
           <span class="flex-1 truncate">{{ connection.name }}</span>
         </button>
       }
-      @for (group of connections.grouped().folders; track group.folder.id) {
+      @for (group of connections.grouped().stacks; track group.stack.id) {
         <div class="px-3 pt-1.5 pb-0.5 text-[10px] font-medium tracking-wide text-muted-foreground uppercase">
-          {{ group.folder.name }}
+          {{ group.stack.name }}
         </div>
         @for (connection of group.connections; track connection.id) {
           <button

ui/src/app/file-panel/file-panel.ts

@@ -89,7 +89,7 @@ export class FilePanel {
   pickConnection(connection: SavedConnection): void {
     this.menuOpen.set(false);
     this.activate();
-    void this.panels.connectPanel(this.side(), connection, connection.name);
+    void this.panels.connectPanel(this.side(), connection, connection.name, connection.localDir);
   }
 
   toggleMenu(): void {