feat: link related precedents across court instances (SCHEMA_V11)

Add ability to mark case_law records as related (e.g. same appeal
through ועדת ערר → מנהלי → עליון):
- DB: case_law_relations join table (bidirectional, V11 migration)
- DB CRUD: add/remove/get_case_law_relations
- Service: get_precedent() now returns related_cases[]
- MCP: precedent_link_cases + precedent_unlink_cases tools
- REST: POST/DELETE /api/precedent-library/{id}/relations
- UI: RelatedCasesSection on detail page with search dialog and unlink

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web-ui/src/app/precedents/[id]/page.tsx

@@ -11,6 +11,7 @@ import { Skeleton } from "@/components/ui/skeleton";
 import { usePrecedent } from "@/lib/api/precedent-library";
 import { PrecedentEditSheet } from "@/components/precedents/precedent-edit-sheet";
 import { ExtractedHalachotSection } from "@/components/precedents/extracted-halachot";
+import { RelatedCasesSection } from "@/components/precedents/link-related-dialog";
 
 const PRACTICE_AREA_LABELS: Record<string, string> = {
   rishuy_uvniya: "רישוי ובנייה",
@@ -152,6 +153,15 @@ export default function PrecedentDetailPage({
               </CardContent>
             </Card>
 
+            <Card className="bg-surface border-rule shadow-sm">
+              <CardContent className="px-6 py-5">
+                <RelatedCasesSection
+                  caseId={id}
+                  related={data.related_cases ?? []}
+                />
+              </CardContent>
+            </Card>
+
             <Card className="bg-surface border-rule shadow-sm">
               <CardContent className="px-6 py-5">
                 <ExtractedHalachotSection halachot={data.halachot ?? []} />