feat(ui): breadcrumb navigation across nested pages

Adds a breadcrumb trail to nested views for orientation. Mechanism: a
{% block breadcrumb %} slot in base.html (+ styling) and a shared crumbs()
macro in templates/_macros.html; each nested page fills the block with its
trail (root→current, last item is the current page). Pages without the block
render no bar, so top-level nav roots stay clean.

Applied to: Ansible (browse, schedules, playbook editor, run detail) +
inventory (targets/groups + detail), host_agent (fleet, host detail,
settings), hosts form, settings tabs (ansible/auth/notifications/plugins/
reports + plugin detail), dashboard (list, edit), and alerts (rule form,
maintenance + new). Dynamic labels (host/target/run/dashboard names) come
from the page context — no route changes. All 60 templates Jinja-compile.

Task #873.

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

steward/templates/settings/ansible.html

@@ -1,6 +1,8 @@
 {# steward/templates/settings/ansible.html #}
 {% extends "base.html" %}
+{% from "_macros.html" import crumbs %}
 {% block title %}Settings — Ansible — Steward{% endblock %}
+{% block breadcrumb %}{{ crumbs([("Settings", "/settings/"), ("Ansible", "")]) }}{% endblock %}
 {% block content %}
 {% set active_tab = "ansible" %}
 {% include "settings/_tabs.html" %}

steward/templates/settings/auth.html

@@ -1,6 +1,8 @@
 {# steward/templates/settings/auth.html #}
 {% extends "base.html" %}
+{% from "_macros.html" import crumbs %}
 {% block title %}Settings — Auth — Steward{% endblock %}
+{% block breadcrumb %}{{ crumbs([("Settings", "/settings/"), ("Authentication", "")]) }}{% endblock %}
 {% block content %}
 {% set active_tab = "auth" %}
 {% include "settings/_tabs.html" %}

steward/templates/settings/notifications.html

@@ -1,6 +1,8 @@
 {# steward/templates/settings/notifications.html #}
 {% extends "base.html" %}
+{% from "_macros.html" import crumbs %}
 {% block title %}Settings — Notifications — Steward{% endblock %}
+{% block breadcrumb %}{{ crumbs([("Settings", "/settings/"), ("Notifications", "")]) }}{% endblock %}
 {% block content %}
 {% set active_tab = "notifications" %}
 {% include "settings/_tabs.html" %}

steward/templates/settings/plugin_detail.html

@@ -1,6 +1,8 @@
 {# steward/templates/settings/plugin_detail.html #}
 {% extends "base.html" %}
+{% from "_macros.html" import crumbs %}
 {% block title %}{{ plugin.get('name', plugin._dir) }} Settings — Steward{% endblock %}
+{% block breadcrumb %}{{ crumbs([("Settings", "/settings/"), ("Plugins", "/settings/plugins/"), (plugin.get('name', plugin._dir), "")]) }}{% endblock %}
 {% block content %}
 {% set active_tab = "plugins" %}
 {% include "settings/_tabs.html" %}

steward/templates/settings/plugins.html

@@ -1,6 +1,8 @@
 {# steward/templates/settings/plugins.html #}
 {% extends "base.html" %}
+{% from "_macros.html" import crumbs %}
 {% block title %}Settings — Plugins — Steward{% endblock %}
+{% block breadcrumb %}{{ crumbs([("Settings", "/settings/"), ("Plugins", "")]) }}{% endblock %}
 {% block content %}
 {% set active_tab = "plugins" %}
 {% include "settings/_tabs.html" %}

steward/templates/settings/reports.html

@@ -1,6 +1,8 @@
 {# steward/templates/settings/reports.html #}
 {% extends "base.html" %}
+{% from "_macros.html" import crumbs %}
 {% block title %}Settings — Reports — Steward{% endblock %}
+{% block breadcrumb %}{{ crumbs([("Settings", "/settings/"), ("Reports", "")]) }}{% endblock %}
 {% block content %}
 {% set active_tab = "reports" %}
 {% include "settings/_tabs.html" %}