feat(host_agent): horizontal zebra-striped fleet widget rows

Restore the host_agent fleet-glance widget to one horizontal row per host
(name left, metric cells + sparklines right) instead of the multi-column
block grid, and zebra-stripe odd rows so adjacent hosts read as distinct.
Names still wrap rather than hard-truncate.

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

plugins/host_agent/templates/widget_table.html

@@ -1,37 +1,41 @@
-{# host_agent widget — fleet glance. Per host: name on its own line (never
-   truncated), then a row of metric cells (cpu/mem/disk/load), each value with a
-   trend sparkline beneath it — the host-page AGENT panel, on the dashboard. #}
+{# host_agent widget — fleet glance. One horizontal row per host, zebra-striped
+   so adjacent hosts read as distinct groupings: health dot + host name on the
+   left, metric cells (cpu/mem/disk/load) each with a trend sparkline laid out
+   horizontally on the right. The name wraps (never hard-truncated) but the row
+   stays horizontal. #}
 {% from "_macros.html" import metric_style %}
 {% if rows %}
 {% macro metric_cell(label, value, fmt, svg, style="", title="") %}
-<div style="min-width:74px;flex:0 0 auto;" title="{{ title }}">
-  <div style="font-size:0.66rem;color:var(--text-dim);text-transform:uppercase;letter-spacing:0.03em;">{{ label }}</div>
+<div style="min-width:62px;flex:0 0 auto;" title="{{ title }}">
+  <div style="font-size:0.62rem;color:var(--text-dim);text-transform:uppercase;letter-spacing:0.03em;">{{ label }}</div>
   <div style="font-weight:600;font-size:0.8rem;font-variant-numeric:tabular-nums;{{ style }}">
     {% if value is not none %}{{ fmt|format(value) }}{% else %}—{% endif %}
   </div>
   <div style="line-height:0;height:16px;">{{ svg | safe }}</div>
 </div>
 {% endmacro %}
-<div class="host-blocks">
+<div class="host-fleet">
   {% for r in rows %}
   {% set stale = r.stale %}
-  <div style="padding:0.55rem 0;border-bottom:1px solid var(--border);">
-    {# Line 1 — health dot + full host name (own line) + last seen #}
-    <div style="display:flex;align-items:center;gap:0.5rem;">
+  <div style="display:flex;align-items:center;gap:0.6rem 1rem;flex-wrap:wrap;padding:0.5rem 0.6rem;border-radius:4px;{% if loop.index0 % 2 %}background:var(--bg-elevated);{% endif %}">
+    {# Left — health dot + full host name (wraps, never truncated) + last seen #}
+    <div style="display:flex;align-items:center;gap:0.5rem;flex:1 1 150px;min-width:120px;">
       <span class="dot {% if stale %}dot-dim{% elif (r.cpu_pct or 0) >= 90 or (r.mem_used_pct or 0) >= 90 or (r.disk_worst or 0) >= 90 %}dot-warn{% else %}dot-up{% endif %}"
             style="flex-shrink:0;"
             title="{% if stale %}stale / no recent data{% else %}warns at CPU/memory ≥90% or any disk mount ≥90% (the 'disk /' figure shows root only){% endif %}"></span>
-      {% if session.user_id %}
-      <a href="/hosts/{{ r.host.id }}" style="font-weight:600;font-size:0.85rem;overflow-wrap:anywhere;">{{ r.host.name }}</a>
-      {% else %}
-      <span style="font-weight:600;font-size:0.85rem;overflow-wrap:anywhere;">{{ r.host.name }}</span>
-      {% endif %}
-      <span style="margin-left:auto;font-size:0.72rem;color:var(--text-dim);flex-shrink:0;">
-        {{ r.reg.last_seen_at.strftime("%H:%M:%S") if r.reg.last_seen_at else "never" }}
+      <span style="min-width:0;">
+        {% if session.user_id %}
+        <a href="/hosts/{{ r.host.id }}" style="font-weight:600;font-size:0.85rem;overflow-wrap:anywhere;">{{ r.host.name }}</a>
+        {% else %}
+        <span style="font-weight:600;font-size:0.85rem;overflow-wrap:anywhere;">{{ r.host.name }}</span>
+        {% endif %}
+        <span style="display:block;font-size:0.7rem;color:var(--text-dim);">
+          {{ r.reg.last_seen_at.strftime("%H:%M:%S") if r.reg.last_seen_at else "never" }}
+        </span>
       </span>
     </div>
-    {# Line 2 — metric cells with value + trend; wraps instead of truncating #}
-    <div style="display:flex;flex-wrap:wrap;gap:0.4rem 1.1rem;margin-top:0.35rem;padding-left:1.1rem;">
+    {# Right — metric cells with value + trend, laid out horizontally #}
+    <div style="display:flex;flex-wrap:wrap;gap:0.4rem 1rem;justify-content:flex-end;">
       {{ metric_cell("cpu", r.cpu_pct, "%.0f%%", r.sparks.cpu, metric_style(r.cpu_pct), "Average CPU utilization") }}
       {{ metric_cell("mem", r.mem_used_pct, "%.0f%%", r.sparks.mem, metric_style(r.mem_used_pct), "Memory in use") }}
       {{ metric_cell("disk /", r.disk_root, "%.0f%%", r.sparks.disk, metric_style(r.disk_root), "Root filesystem (/) usage") }}