Always render VM list; surface SPICE connect target for diagnosis

- Auto-connect (single-VM shortcut and autostart match) now renders the
  VM list first instead of skipping straight to the connect attempt.
  With cluster dedup collapsing 3 duplicate entries down to 1, the VM
  vanished from the screen entirely whenever the connection failed.
- proxmox:connect now returns the resolved host:port it handed to
  remote-viewer, shown in the success notice, so connection failures
  (e.g. Proxmox handing out a cluster-internal node address the client
  cannot route to) can be diagnosed without racing delete-this-file.

src/main.js

@@ -222,9 +222,9 @@ ipcMain.handle('proxmox:connect', async (_e, { host, node, vmid }) => {
     const entry = clients.find((c) => c.host === host) || clients[0];
     if (!entry) throw new Error('Nicht angemeldet.');
     const params = await entry.client.getSpiceTicket(node, vmid);
-    const vvPath = buildVVFile(params, vmid, entry.client);
+    const { vvPath, target } = buildVVFile(params, vmid, entry.client);
     launchRemoteViewer(vvPath);
-    return { success: true };
+    return { success: true, target };
   } catch (err) {
     return { success: false, error: err.message };
   }
@@ -290,7 +290,12 @@ function buildVVFile(params, vmid, client) {
 
   const vvPath = path.join(os.tmpdir(), `spice-${vmid}-${Date.now()}.vv`);
   fs.writeFileSync(vvPath, lines.join('\n') + '\n', { mode: 0o600 });
-  return vvPath;
+
+  // Surfaced to the renderer so a failed connection (e.g. Proxmox handing out
+  // a cluster-internal node address the client can't route to) is diagnosable
+  // without having to catch the .vv file before remote-viewer deletes it.
+  const port = params['tls-port'] || params.port || '?';
+  return { vvPath, target: `${host}:${port}` };
 }
 
 // VirtViewer's Windows installer names its folder after the bundled version