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/browse.html

@@ -7,6 +7,8 @@
       {% if session.user_role == 'admin' %}
       <a href="/ansible/playbooks/new" class="btn btn-sm">New playbook</a>
       {% endif %}
+      <a href="/ansible/inventory/targets" class="btn btn-ghost btn-sm">Inventory</a>
+      <a href="/ansible/schedules" class="btn btn-ghost btn-sm">Schedules</a>
       <a href="/ansible/" class="btn btn-ghost btn-sm">← Run History</a>
     </div>
 </div>