feat(widgets): Routers and Hosts problem rows say since when (#5810)

Routers: a router in trouble reads 'started 2h ago' or 'all of the last
24 h', from problem_since over the day's history, read for the troubled
routers only (a certificate's problem carries its own date). Hosts: a
down host reads 'a monitor is down for 3h'; host_glance keeps the
down_since host_status already had.

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

plugins/traefik/routes.py

@@ -496,10 +496,21 @@ async def widget():
             r["cert"]["grade"] = grade
             if _GRADE_ORDER.get(grade, 2) < _GRADE_ORDER[r["state"]]:
                 left = cert_left(r["cert"]["days"])     # "12 days", "expires today", "expired …"
+                r["by_cert"] = True
                 r["state"], r["why"] = grade, (
                     f"certificate expires in {left}" if left[0].isdigit() else f"certificate {left}")
     problems, healthy = split_routers(current)
     healthy.sort(key=lambda r: -(r["latest"].request_rate or 0))
+    # Since when, from the day's history, for problems the traffic shows (a
+    # certificate's says its own date). Only the routers in trouble are read.
+    traffic = [r for r in problems if not r.get("by_cert")]
+    if traffic:
+        since = now - WIDGET_SINCE
+        async with current_app.db_sessionmaker() as db:
+            history = await router_history(db, [r["name"] for r in traffic], since,
+                                           bucket_seconds(since))
+        for r in traffic:
+            r["since"], r["since_before"] = problem_since(history[r["name"]], thresholds)
     # With no router domains to go on, certificates can't sit on their
     # routers: the expiring ones are listed after the routers instead.
     loose = [] if domains is not None else sorted(
@@ -516,6 +527,8 @@ async def widget():
 
 # Healthy routers on the dashboard widget (the busiest); the page lists all.
 ROUTERS_SHOWN = 6
+# How far back the widget looks for when a router's problem began.
+WIDGET_SINCE = timedelta(hours=24)
 
 
 @traefik_bp.get("/widget/access_log")