feat(alerts): always-visible dismiss/ack actions + Dismiss all (service, endpoint, UI)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/components/alerts/alerts-page-shell.tsx

@@ -4,10 +4,11 @@ import { useState } from 'react';
 import { ShieldAlert } from 'lucide-react';
 
 import { PageHeader } from '@/components/shared/page-header';
+import { Button } from '@/components/ui/button';
 import { Tabs, TabsList, TabsTrigger, TabsContent } from '@/components/ui/tabs';
 import { Skeleton } from '@/components/ui/skeleton';
 import { AlertCard, AlertCardEmpty } from './alert-card';
-import { useAlertCount, useAlertList, useAlertRealtime } from './use-alerts';
+import { useAlertCount, useAlertList, useAlertRealtime, useDismissAll } from './use-alerts';
 import type { AlertStatus } from './types';
 
 /**
@@ -30,6 +31,7 @@ export function AlertsPageShell({ embedded = false }: AlertsPageShellProps = {})
 
   const total = count?.total ?? 0;
   const alerts = data?.data ?? [];
+  const dismissAll = useDismissAll();
 
   return (
     <div className={embedded ? 'space-y-3' : 'space-y-6'}>
@@ -62,6 +64,18 @@ export function AlertsPageShell({ embedded = false }: AlertsPageShellProps = {})
         </TabsList>
 
         <TabsContent value={tab} className="mt-4 space-y-2">
+          {tab === 'open' && alerts.length > 0 ? (
+            <div className="flex justify-end">
+              <Button
+                variant="ghost"
+                size="sm"
+                onClick={() => dismissAll.mutate({})}
+                disabled={dismissAll.isPending}
+              >
+                Dismiss all
+              </Button>
+            </div>
+          ) : null}
           {isLoading ? (
             <div className="space-y-2">
               <Skeleton className="h-20 w-full" />