Support multiple standalone Proxmox hosts with shared credentials

Comma-separated host list logs into every host, merges VM lists tagged
by origin host, and routes SPICE connections to the right one. Also
adds a username format hint (user@realm) on the login form.

src/renderer/login.html

@@ -17,12 +17,14 @@
 
     <form id="loginForm" autocomplete="on">
       <div class="field">
-        <label for="host">Proxmox Host</label>
+        <label for="host">Proxmox Host(s)</label>
         <input type="text" id="host" placeholder="pve.example.com" autocomplete="url" spellcheck="false">
+        <div class="field-hint">Mehrere eigenständige Hosts mit denselben Zugangsdaten? Mit Komma trennen, z. B. pve1.example.com, pve2.example.com</div>
       </div>
       <div class="field">
         <label for="username">Benutzer</label>
-        <input type="text" id="username" placeholder="user@pam" autocomplete="username" spellcheck="false">
+        <input type="text" id="username" placeholder="root@pam" autocomplete="username" spellcheck="false">
+        <div class="field-hint">Format: Benutzer@Realm — z. B. root@pam</div>
       </div>
       <div class="field">
         <label for="password">Passwort</label>

src/renderer/styles.css

@@ -76,6 +76,13 @@ body.login-page {
   margin-bottom: 0.4rem;
 }
 
+.field-hint {
+  font-size: 0.72rem;
+  color: var(--muted);
+  margin-top: 0.35rem;
+  line-height: 1.4;
+}
+
 input[type="text"],
 input[type="password"] {
   width: 100%;

src/renderer/vms.js

@@ -91,6 +91,9 @@ loadVMs();
 // ── Render ────────────────────────────────────────────────
 
 function renderList(vms) {
+  // Only show the host when there's more than one — single-host setups don't need the noise.
+  const multiHost = new Set(vms.map((vm) => vm.host)).size > 1;
+
   listEl.innerHTML = vms
     .map(
       (vm) => `
@@ -99,12 +102,13 @@ function renderList(vms) {
           <div class="vm-name">${esc(vm.name)}</div>
           <div class="vm-meta">
             <span class="status-dot"></span>
-            Läuft &nbsp;·&nbsp; Node: ${esc(vm.node)} &nbsp;·&nbsp; ID: ${vm.vmid}
+            Läuft &nbsp;·&nbsp; ${multiHost ? `Host: ${esc(vm.host)} &nbsp;·&nbsp; ` : ''}Node: ${esc(vm.node)} &nbsp;·&nbsp; ID: ${vm.vmid}
           </div>
         </div>
         <button
           class="btn-connect"
           data-vmid="${vm.vmid}"
+          data-host="${esc(vm.host)}"
           data-node="${esc(vm.node)}"
           data-name="${esc(vm.name)}"
         >Verbinden</button>
@@ -115,7 +119,12 @@ function renderList(vms) {
 
   listEl.querySelectorAll('.btn-connect').forEach((btn) => {
     btn.addEventListener('click', () =>
-      connectVM({ vmid: btn.dataset.vmid, node: btn.dataset.node, name: btn.dataset.name })
+      connectVM({
+        vmid: btn.dataset.vmid,
+        host: btn.dataset.host,
+        node: btn.dataset.node,
+        name: btn.dataset.name,
+      })
     );
   });