feat(ansible): cross-link inventory/schedules/browse for discoverability

The inventory CRUD UI (/ansible/inventory/targets + /groups) existed but was
unreachable from the main Ansible pages — only a buried text hint pointed to
it. Add an "Inventory" button to the Runs, Browse, and Schedules headers, and
"← Ansible" back-links on the inventory target/group pages, so the targeting
features (manual runs, schedules, Deploy-via-Ansible) are findable.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

steward/templates/ansible/index.html

@@ -4,6 +4,7 @@
 <div style="display:flex;align-items:center;justify-content:space-between;margin-bottom:1.5rem;">
     <h1 class="page-title" style="margin-bottom:0;">Ansible Runs</h1>
     <div style="display:flex;gap:0.5rem;">
+      <a href="/ansible/inventory/targets" class="btn btn-ghost">Inventory</a>
       <a href="/ansible/schedules" class="btn btn-ghost">Schedules</a>
       <a href="/ansible/browse" class="btn">Browse Playbooks</a>
     </div>