feat: retry failed extractions button on pipeline page

- POST /api/ops/pipeline/retry-failed endpoint resets extraction_failed
  docs to parsed, deletes failed intelligence rows, and re-enqueues
  them (batch of 200)
- Scheduler now auto-retries extraction_failed docs every ~10 minutes
  (100 per cycle, 60-min cooldown per doc)
- Pipeline page shows 'Retry Failed (N)' button when extraction_failed
  count > 0, with pending/success/error states

frontend/src/pages/OpsPipeline.tsx

@@ -1,5 +1,5 @@
 import { useState, useEffect } from 'react';
-import { usePipelineHealth } from '../api/hooks';
+import { usePipelineHealth, useRetryFailedExtractions } from '../api/hooks';
 import { LoadingSpinner, DateRangeSelector, Card } from '../components/ui';
 
 const QUEUE_LABELS: Record<string, string> = {
@@ -53,6 +53,7 @@ export function OpsPipelinePage() {
   const [hours, setHours] = useState(24);
   const { data, isLoading } = usePipelineHealth(hours);
   const stream = usePipelineStream();
+  const retryMutation = useRetryFailedExtractions();
 
   if (isLoading) return <LoadingSpinner />;
 
@@ -70,6 +71,8 @@ export function OpsPipelinePage() {
         .map((s) => [s.status, s.doc_count]),
     );
 
+  const failedCount = docStages['extraction_failed'] ?? 0;
+
   // Separate DLQ entries from regular queues
   const dlqEntries = Object.entries(queueDepths).filter(([k]) => k.startsWith('dlq:'));
   const regularQueues = Object.entries(QUEUE_LABELS);
@@ -79,6 +82,22 @@ export function OpsPipelinePage() {
       <div className="flex items-center justify-between">
         <h1 className="text-xl font-semibold text-gray-100">Pipeline Health</h1>
         <div className="flex items-center gap-3">
+          {failedCount > 0 && (
+            <button
+              type="button"
+              onClick={() => retryMutation.mutate()}
+              disabled={retryMutation.isPending}
+              className="rounded-md bg-amber-600 px-3 py-1.5 text-xs font-medium text-white hover:bg-amber-500 disabled:opacity-50"
+            >
+              {retryMutation.isPending ? 'Retrying…' : `Retry Failed (${failedCount})`}
+            </button>
+          )}
+          {retryMutation.isSuccess && (
+            <span className="text-xs text-green-400">{retryMutation.data.message}</span>
+          )}
+          {retryMutation.isError && (
+            <span className="text-xs text-red-400">Retry failed</span>
+          )}
           {stream && (
             <span className="flex items-center gap-1.5 text-xs text-green-400">
               <span className="inline-block h-2 w-2 rounded-full bg-green-400 animate-pulse" aria-hidden="true" />