feat(matching-runs): attach origin_run_id to new suggestions and expose pairs-per-run API

- Extend saveMatchingResults(eventId, suggestions, runId) and set originRunId
- Scheduler/Admin run-now: always pass runId
- Admin API: GET /api/admin/events/:slug/matching-runs/:runId/suggestions
- Prisma: add compound index on (origin_run_id, status)
- Frontend: add getRunSuggestions, expand row in MatchingRunsSection with 'Pairs created in this run' wording

frontend/src/services/api.js

@@ -455,6 +455,16 @@ export const adminAPI = {
     const data = await fetchAPI(`/admin/events/${slug}/matching-runs?${params.toString()}`);
     return data;
   },
+
+  async getRunSuggestions(slug, runId, { onlyAssigned = true, includeNotFound = false, limit = 100 } = {}) {
+    const params = new URLSearchParams({
+      onlyAssigned: String(onlyAssigned),
+      includeNotFound: String(includeNotFound),
+      limit: String(limit),
+    });
+    const data = await fetchAPI(`/admin/events/${slug}/matching-runs/${runId}/suggestions?${params.toString()}`);
+    return data;
+  },
 };
 
 export { ApiError };