style: clear whitespace, unused-import and blank-line lint

Strip trailing whitespace, drop unused imports/variables/global statements,
split multi-imports, fix E3xx/E1xx spacing and E712 comparisons. No behaviour
change; only E501 long lines remain in flake8.

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

hbd/server/http.py

@@ -109,6 +109,7 @@ def _insert_threshold_metric(thresholds: dict, metric_path: str, values: dict) -
         else:
             thresholds[plugin].setdefault(intermediate, {})[leaf] = cfg
 
+
 def _render_template(html_str: str, **context) -> str:
     tmpl = jinja2.Template(html_str)
     return tmpl.render(**context)
@@ -563,7 +564,7 @@ async def start(
         if err:
             return err
         hostname = request.match_info.get("hostname")
-        
+
         if hostname not in hbdclass.Host.hosts:
             return web.json_response({"error": f"Host '{hostname}' not found"}, status=404)
 
@@ -582,7 +583,7 @@ async def start(
                     "data": data,
                     "sample_count": len(samples),
                 }
-        
+
         return web.json_response({
             "hostname": hostname,
             "plugins": plugins_summary,
@@ -602,23 +603,23 @@ async def start(
         host = hbdclass.Host.hosts[hostname]
         if not _can_view_host(user, host):
             return web.json_response({"error": "Forbidden"}, status=403)
-        
+
         # Get limit from query parameter
         limit = request.rel_url.query.get("limit", "10")
         try:
             limit = int(limit)
         except ValueError:
             limit = 10
-        
+
         # Get plugin data
         samples = host.get_plugin_data(plugin_name, limit=limit)
-        
+
         if not samples:
             return web.json_response(
                 {"error": f"No data for plugin '{plugin_name}' on host '{hostname}'"},
                 status=404
             )
-        
+
         # Format samples
         formatted_samples = [
             {
@@ -627,7 +628,7 @@ async def start(
             }
             for ts, data in samples
         ]
-        
+
         return web.json_response({
             "hostname": hostname,
             "plugin": plugin_name,
@@ -648,17 +649,17 @@ async def start(
         host = hbdclass.Host.hosts[hostname]
         if not _can_view_host(user, host):
             return web.json_response({"error": "Forbidden"}, status=403)
-        
+
         # Get alert states
         alerts = []
         for metric_path, alert_state in host.alert_states.items():
             alerts.append(alert_state.to_dict())
-        
+
         # Get summary if threshold_checker available
         summary = {"ok": 0, "warning": 0, "critical": 0, "unknown": 0}
         if threshold_checker:
             summary = threshold_checker.get_alert_summary(host.alert_states)
-        
+
         return web.json_response({
             "hostname": hostname,
             "alerts": alerts,
@@ -684,31 +685,31 @@ async def start(
                     state for state in host.alert_states.values()
                     if state.level != AlertLevel.OK
                 ]
-            
+
             for alert in active_alerts:
                 alert_dict = alert.to_dict()
                 alert_dict["hostname"] = hostname
                 all_alerts.append(alert_dict)
-        
+
         # Sort by level (critical first) then by hostname
         level_order = {"CRITICAL": 0, "WARNING": 1, "UNKNOWN": 2, "OK": 3}
         all_alerts.sort(
             key=lambda a: (level_order.get(a["level"], 99), a["hostname"], a["metric_path"])
         )
-        
+
         # Get summary counts
         summary = {"critical": 0, "warning": 0, "unknown": 0, "total": len(all_alerts)}
         for alert in all_alerts:
             level = alert["level"].lower()
             if level in summary:
                 summary[level] += 1
-        
+
         return web.json_response({
             "alerts": all_alerts,
             "summary": summary,
             "host_count": len(hbdclass.Host.hosts),
         })
-    
+
     async def api_acknowledge_alert(request):
         """Acknowledge an alert to stop reminder notifications."""
         user, err = _require_auth(request)
@@ -721,22 +722,22 @@ async def start(
                 {"error": "Invalid JSON in request body"},
                 status=400
             )
-        
+
         hostname = data.get("hostname")
         metric_path = data.get("metric_path")
-        
+
         if not hostname or not metric_path:
             return web.json_response(
                 {"error": "Missing required fields: hostname and metric_path"},
                 status=400
             )
-        
+
         if hostname not in hbdclass.Host.hosts:
             return web.json_response(
                 {"error": f"Host '{hostname}' not found"},
                 status=404
             )
-        
+
         host = hbdclass.Host.hosts[hostname]
         if not _can_view_host(user, host):
             return web.json_response({"error": "Forbidden"}, status=403)
@@ -746,10 +747,10 @@ async def start(
                 {"error": f"Alert '{metric_path}' not found for host '{hostname}'"},
                 status=404
             )
-        
+
         alert_state = host.alert_states[metric_path]
         alert_state.acknowledge()
-        
+
         return web.json_response({
             "success": True,
             "hostname": hostname,
@@ -1132,7 +1133,6 @@ async def start(
                 elif is_mon:
                     monitored.append(hostname)
 
-
         # Resolve notification channel configs for display
         notif_channels = []
         if current_user: