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>

src/shared/types.ts

@@ -27,13 +27,18 @@ export interface ConnectionConfig {
 
 export interface SavedConnection extends ConnectionConfig {
 	id: string;
-	folderId: string | null;
+	stackId: string | null;
 	name: string;
+	/** Other-panel local dir applied when that panel is local and untouched. */
+	localDir?: string | null;
 }
 
-export interface ConnFolder {
+/** A named group of connections that can be opened together as tabs. */
+export interface Stack {
 	id: string;
 	name: string;
+	/** Collapsed in the connection-manager list (UI state, persisted). */
+	collapsed?: boolean;
 }
 
 /** A concrete host alias resolved from ~/.ssh/config (read-only). */
@@ -47,8 +52,8 @@ export interface SshConfigHost {
 }
 
 export interface ConnectionsFile {
-	version: 1;
-	folders: ConnFolder[];
+	version: 2;
+	stacks: Stack[];
 	connections: SavedConnection[];
 }