Tighten Manage dialog action-bar copy and cluster subtitle

Three small frictions on the Manage existing-connection dialog:

- Save button read 'Update Node' (technical, paired with 'Add Node'
  when adding). Switch to 'Save changes' / 'Add node' so the editing
  case uses standard form-save vocabulary.

- 'Test Connection' was Title Case while sibling buttons in the same
  bar were sentence case ('Pause connection', 'Delete connection').
  Normalize to 'Test connection' / 'Testing…'.

- Cluster Manage dialog subtitle read 'Proxmox VE cluster · Editing
  via contact node delly (https://delly:8006) · API + Pulse Agent'.
  The 'Editing via' clause was awkward and didn't add information the
  user couldn't infer from the dialog body. Drop it: now reads
  'Proxmox VE cluster · delly (https://delly:8006) · API + Pulse
  Agent'.

frontend-modern/src/components/Settings/InfrastructureWorkspace.tsx

@@ -877,7 +877,10 @@ const InfrastructureWorkspaceContent: Component<InfrastructureWorkspaceProps> =
     const row = editingRow();
     if (row?.isCluster) {
       const contact = connection.name || connection.address || 'contact node';
-      return `${label} cluster · Editing via contact node ${contact}${connection.address ? ` (${connection.address})` : ''}${methods}`;
+      // Drop the 'Editing via' phrasing that read awkwardly; just identify
+      // the contact node and address. The dialog body and the row the user
+      // came from already make the editing context clear.
+      return `${label} cluster · ${contact}${connection.address ? ` (${connection.address})` : ''}${methods}`;
     }
     return `${label}${connection.address ? ` · ${connection.address}` : ''}${methods}`;
   });

frontend-modern/src/components/Settings/NodeModalStatusFooter.tsx

@@ -154,7 +154,7 @@ export const NodeModalStatusFooter: Component<NodeModalStatusFooterProps> = (pro
               disabled={state.isTesting() || props.togglePending || props.deletePending}
               class="px-4 py-2 text-sm border border-border text-base-content rounded-md hover:bg-surface-hover transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
             >
-              {state.isTesting() ? 'Testing...' : 'Test Connection'}
+              {state.isTesting() ? 'Testing…' : 'Test connection'}
             </button>
           </Show>
         </div>
@@ -213,7 +213,7 @@ export const NodeModalStatusFooter: Component<NodeModalStatusFooterProps> = (pro
               disabled={props.togglePending || props.deletePending}
               class="px-4 py-2 text-sm bg-blue-600 text-white rounded-md hover:bg-blue-700 transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
             >
-              {state.isEditingExistingNode() ? 'Update' : 'Add'} Node
+              {state.isEditingExistingNode() ? 'Save changes' : 'Add node'}
             </button>
           </Show>
         </div>