fix(ui): allow creating a secret once the list is no longer empty

[arminfauland]

Problem

The create secret button only exists inside the empty state:

@if (!loading() && !error() && secrets().length === 0) {
  <app-button action variant="secondary" (click)="openCreateModal()">
    {{ 'secrets.create_button' | transloco }}

openCreateModal() is referenced exactly once in the template. As soon as one secret exists the block stops rendering, and the secrets manager offers no other way to create another one.

The remaining routes are not discoverable:

• the deep link /(modal:secrets/create/<name>)
• the run dialog, which links there — but only when a workflow already references a missing secret

So a user who has set up their first secret and later wants a second one finds a dialog that can only list and edit.

Fix

Adds the same button above the list, so it is reachable in both states. Reuses the existing secrets.create_button key — no translation changes needed.

<div class="flex justify-end mb-3">
  <app-button variant="secondary" size="sm" (click)="openCreateModal()">
    {{ 'secrets.create_button' | transloco }}
  </app-button>
</div>

secondary and sm are both valid members of ButtonVariant / ButtonSize.

Verification

• nx lint ui — passes
• nx build ui — succeeds (the bundle-budget warning is pre-existing)
• Found on a running instance: four secrets existed and the dialog offered no way to add a fifth.