(ui) Add consistent page headers to key views

Introduce a shared page-header pattern with kicker, title, subtitle, and
actions, then apply it to the dashboard, host detail, run detail, snapshot
detail, and retention plan pages.

Scope the global app header styles to avoid leaking sticky navigation styles
onto page-level headers, and add view assertions for the new page context.

Refs #28

src/pobsync_backend/templates/pobsync_backend/base.html

@@ -43,7 +43,7 @@
 	      outline: 3px solid rgba(7, 95, 174, 0.24);
 	      outline-offset: 2px;
 	    }
-	    header {
+	    body > header {
 	      background: var(--panel);
 	      border-bottom: 1px solid var(--border);
 	      box-shadow: var(--shadow-sm);
@@ -105,6 +105,35 @@
 	    }
 	    p { margin: 0 0 12px; }
 	    p:last-child { margin-bottom: 0; }
+	    .page-header {
+	      align-items: end;
+	      display: flex;
+	      gap: 18px;
+	      justify-content: space-between;
+	      margin-bottom: 20px;
+	    }
+	    .page-title {
+	      display: grid;
+	      gap: 5px;
+	      min-width: 0;
+	    }
+	    .page-title h1 { margin-bottom: 0; overflow-wrap: anywhere; }
+	    .page-kicker {
+	      color: var(--muted);
+	      font-size: 12px;
+	      font-weight: 750;
+	      letter-spacing: 0.05em;
+	      text-transform: uppercase;
+	    }
+	    .page-subtitle {
+	      color: var(--muted);
+	      max-width: 760px;
+	    }
+	    .page-header .actions {
+	      flex: 0 0 auto;
+	      justify-content: flex-end;
+	      margin-bottom: 0;
+	    }
 	    .grid {
 	      display: grid;
 	      grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
@@ -483,7 +512,7 @@
       padding: 0;
     }
 	    @media (max-width: 800px) {
-	      header { padding: 0 14px; position: static; }
+	      body > header { padding: 0 14px; position: static; }
 	      main { padding: 18px 14px 32px; }
 	      nav {
 	        align-items: flex-start;
@@ -493,6 +522,11 @@
 	      }
 	      nav strong { flex-basis: 100%; margin-right: 0; }
 	      nav .spacer { display: none; }
+	      .page-header {
+	        align-items: stretch;
+	        display: grid;
+	      }
+	      .page-header .actions { justify-content: flex-start; }
 	      .two-col { grid-template-columns: 1fr; }
 	      .host-card-header { display: grid; }
       .host-card-status { justify-content: flex-start; max-width: none; }

src/pobsync_backend/templates/pobsync_backend/dashboard.html

@@ -3,12 +3,17 @@
 {% block title %}pobsync dashboard{% endblock %}
 
 {% block content %}
+  <header class="page-header">
+    <div class="page-title">
+      <div class="page-kicker">Control panel</div>
       <h1>Dashboard</h1>
-
+      <div class="page-subtitle">Backup health, required action, storage pressure, and recent activity in one place.</div>
+    </div>
     <section class="actions" aria-label="Dashboard actions">
       <a class="button-link" href="{% url 'create_host_config' %}">New host</a>
       <a class="button-link secondary" href="{% url 'edit_global_config' %}">{% if global_config %}Edit global config{% else %}Create global config{% endif %}</a>
     </section>
+  </header>
 
   {% if not global_config or not counts.hosts %}
     <section class="panel">

src/pobsync_backend/templates/pobsync_backend/host_detail.html

@@ -3,8 +3,12 @@
 {% block title %}{{ host.host }} | pobsync{% endblock %}
 
 {% block content %}
+  <header class="page-header">
+    <div class="page-title">
+      <div class="page-kicker">Host</div>
       <h1>{{ host.host }}</h1>
-
+      <div class="page-subtitle">{{ host.address }} · {{ host.enabled|yesno:"enabled,disabled" }}</div>
+    </div>
     <section class="actions" aria-label="Host actions">
       <a class="button-link" href="{% url 'edit_host_config' host.host %}">Edit config</a>
       <form method="post" action="{% url 'discover_host_snapshots' host.host %}">
@@ -26,6 +30,7 @@
         <button type="submit" class="secondary">Run connection preflight</button>
       </form>
     </section>
+  </header>
 
   <section class="grid" aria-label="Host summary">
     <div class="metric"><div class="label">Snapshots</div><div class="value">{{ counts.snapshots }}</div></div>

src/pobsync_backend/templates/pobsync_backend/retention_plan.html

@@ -3,8 +3,12 @@
 {% block title %}Retention plan | {{ host.host }}{% endblock %}
 
 {% block content %}
-  <h1>Retention Plan: {{ host.host }}</h1>
+  <header class="page-header">
-
+    <div class="page-title">
+      <div class="page-kicker">Retention</div>
+      <h1>{{ host.host }}</h1>
+      <div class="page-subtitle">Preview which snapshots stay, which would be deleted, and whether incomplete cleanup is needed.</div>
+    </div>
     <section class="actions" aria-label="Retention filters">
       <a class="button-link" href="{% url 'host_detail' host.host %}">Back to host</a>
       <a class="button-link" href="{% url 'host_retention_plan' host.host %}?kind=scheduled">Scheduled</a>
@@ -12,6 +16,7 @@
       <a class="button-link" href="{% url 'host_retention_plan' host.host %}?kind=all">All</a>
       <a class="button-link" href="{% url 'host_retention_plan' host.host %}?kind={{ kind }}&protect_bases=1">Protect bases</a>
     </section>
+  </header>
 
   <section class="grid" aria-label="Retention plan summary">
     <div class="metric"><div class="label">Kind</div><div class="value">{{ plan.kind }}</div></div>

src/pobsync_backend/templates/pobsync_backend/run_detail.html

@@ -3,8 +3,12 @@
 {% block title %}Run {{ run.id }} | {{ run.host.host }}{% endblock %}
 
 {% block content %}
+  <header class="page-header">
+    <div class="page-title">
+      <div class="page-kicker">Backup run</div>
       <h1>Run {{ run.id }}</h1>
-
+      <div class="page-subtitle">{{ run.host.host }} · {{ run.run_type }} · {{ run.status }}</div>
+    </div>
     <section class="actions" aria-label="Run actions">
       <a class="button-link" href="{% url 'host_detail' run.host.host %}">Back to host</a>
       {% if can_cancel %}
@@ -22,6 +26,7 @@
         {% endif %}
       {% endif %}
     </section>
+  </header>
 
   <section class="grid" aria-label="Run summary">
     <div class="metric"><div class="label">Host</div><div class="value">{{ run.host.host }}</div></div>

src/pobsync_backend/templates/pobsync_backend/snapshot_detail.html

@@ -3,11 +3,16 @@
 {% block title %}Snapshot {{ snapshot.dirname }} | {{ snapshot.host.host }}{% endblock %}
 
 {% block content %}
+  <header class="page-header">
+    <div class="page-title">
+      <div class="page-kicker">Snapshot</div>
       <h1>{{ snapshot.dirname }}</h1>
-
+      <div class="page-subtitle">{{ snapshot.host.host }} · {{ snapshot.kind }} · {{ snapshot.status }}</div>
+    </div>
     <section class="actions" aria-label="Snapshot actions">
       <a class="button-link" href="{% url 'host_detail' snapshot.host.host %}">Back to host</a>
     </section>
+  </header>
 
   <section class="grid" aria-label="Snapshot summary">
     <div class="metric"><div class="label">Host</div><div class="value">{{ snapshot.host.host }}</div></div>

src/pobsync_backend/tests/test_views.py

@@ -101,6 +101,8 @@ class ViewTests(TestCase):
         response = self.client.get(reverse("dashboard"))
 
         self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Control panel")
+        self.assertContains(response, "Backup health, required action, storage pressure, and recent activity in one place.")
         self.assertContains(response, "Dashboard")
         self.assertContains(response, "web-01")
         self.assertContains(response, "20260519-021500Z__ABCDEFGH")
@@ -869,6 +871,8 @@ class ViewTests(TestCase):
         response = self.client.get(reverse("host_detail", args=[host.host]))
 
         self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Host")
+        self.assertContains(response, "web-01.example.test")
         self.assertContains(response, "Effective Config")
         self.assertContains(response, "Backup source:")
         self.assertNotContains(response, "Source root:")
@@ -1425,6 +1429,8 @@ class ViewTests(TestCase):
         response = self.client.get(reverse("run_detail", args=[run.id]))
 
         self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Backup run")
+        self.assertContains(response, "web-01")
         self.assertContains(response, "Failure")
         self.assertContains(response, "transport")
         self.assertContains(response, "Check network connectivity.")
@@ -1615,6 +1621,7 @@ class ViewTests(TestCase):
         response = self.client.get(reverse("snapshot_detail", args=[base.id]))
 
         self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Snapshot")
         self.assertContains(response, base.dirname)
         self.assertContains(response, "BASESNAP")
         self.assertContains(response, "Stats")
@@ -1697,7 +1704,9 @@ class ViewTests(TestCase):
         response = self.client.get(reverse("host_retention_plan", args=[host.host]))
 
         self.assertEqual(response.status_code, 200)
-        self.assertContains(response, "Retention Plan: web-01")
+        self.assertContains(response, "Retention")
+        self.assertContains(response, "Preview which snapshots stay")
+        self.assertContains(response, "web-01")
         self.assertContains(response, old_snapshot.dirname)
         self.assertContains(response, new_snapshot.dirname)
         self.assertContains(response, "newest")