feat(ui): shared |bytes |rate |duration |ago filters and status_class from Settings → Thresholds (#5093)

#5093 "Shared format filters and status_class driven by Settings → Thresholds".

- steward/core/formatting.py: human_bytes (binary units), human_rate,
  human_duration (two largest units), ago (a <time> titled with the absolute
  UTC time) and status_class(value, kind, thresholds) -> ok/warn/crit/unknown,
  which raises on a kind the thresholds don't name.
- app.py registers them as the bytes, rate, duration and ago filters and the
  status_class global; threshold_style is now graded by status_class (and caps
  its weight at 500).
- Replaces the copies: docker's _human_bytes/_human_uptime, core alerts'
  _duration, the host-agent fmt_bps/fmt_bytes macros, the Traefik and UniFi
  byte-rate arithmetic, the swarm-failures ago macro and two uptime spans.
- Tests: a table per helper, and every template compiled against the app's
  filters, so an unknown filter fails CI rather than a page.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugins/traefik/templates/traefik/rows.html

@@ -28,9 +28,8 @@
   {% if global_stat.process_memory_bytes is not none %}
   <span>
     <span style="color:var(--text-muted);">Memory</span>
-    {% set mb = (global_stat.process_memory_bytes / 1048576) %}
     <span style="margin-left:0.4rem;">
-      {% if mb >= 1024 %}{{ "%.1f"|format(mb / 1024) }} GB{% else %}{{ "%.0f"|format(mb) }} MB{% endif %}
+      {{ global_stat.process_memory_bytes|bytes }}
     </span>
   </span>
   {% endif %}
@@ -58,9 +57,7 @@
             <td style="color:var(--text-muted);padding:0.2rem 0;">Bandwidth</td>
             <td style="padding:0.2rem 0.5rem;">
               {% set bps = r.latest.response_bytes_rate %}
-              {% if bps >= 1048576 %}{{ "%.1f"|format(bps / 1048576) }} MB/s
-              {% elif bps >= 1024 %}{{ "%.1f"|format(bps / 1024) }} KB/s
-              {% else %}{{ "%.0f"|format(bps) }} B/s{% endif %}
+              {{ bps|rate }}
             </td>
             <td style="padding:0.2rem 0;"></td>
         </tr>

plugins/traefik/templates/traefik/traffic.html

@@ -20,8 +20,7 @@
   <span>
     <span style="color:var(--text-muted);">Bytes</span>
     <span style="margin-left:0.4rem;">
-      {% set mb = summary.total_bytes / 1048576 %}
-      {% if mb >= 1024 %}{{ "%.1f"|format(mb / 1024) }} GB{% else %}{{ "%.1f"|format(mb) }} MB{% endif %}
+      {{ summary.total_bytes|bytes }}
     </span>
   </span>
 

plugins/traefik/templates/traefik/widget.html

@@ -26,9 +26,7 @@
       <span style="color:var(--text-muted);">bw</span>
       <span style="margin-left:0.3rem;">
         {% set bps = r.latest.response_bytes_rate %}
-        {% if bps >= 1048576 %}{{ "%.1f"|format(bps / 1048576) }}MB/s
-        {% elif bps >= 1024 %}{{ "%.0f"|format(bps / 1024) }}KB/s
-        {% else %}{{ "%.0f"|format(bps) }}B/s{% endif %}
+        {{ bps|rate }}
       </span>
     </span>
     <span title="p95 latency">