feat(web-ui): expose citation-corroboration badge on halachot (X11)

- db.list_halachot: aggregate corroboration_count (distinct positive sources)
  + corroboration_negative from halacha_citation_corroboration (LEFT JOIN)
- web-ui: CorroborationBadge — 'מתוקף · N ציטוטים' at ≥2 (gold), soft single
  citation, danger badge on negative treatment; native title tooltips
- shown in ExtractedHalachotSection (per-precedent) + halacha review panel

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web-ui/src/components/precedents/extracted-halachot.tsx

@@ -2,6 +2,7 @@
 
 import { useMemo, useState } from "react";
 import { Badge } from "@/components/ui/badge";
+import { CorroborationBadge } from "@/components/precedents/corroboration-badge";
 import type { Halacha } from "@/lib/api/precedent-library";
 
 const RULE_TYPE_LABELS: Record<string, string> = {
@@ -148,6 +149,7 @@ export function ExtractedHalachotSection({ halachot }: { halachot: Halacha[] })
                 <Badge variant="outline" className="text-[0.65rem] tabular-nums">
                   ביטחון {h.confidence.toFixed(2)}
                 </Badge>
+                <CorroborationBadge halacha={h} />
                 {h.page_reference ? (
                   <span className="text-[0.7rem] text-ink-muted ms-auto">
                     {h.page_reference}