feat(matching-runs): add per-run aggregate stats and UI display

- Admin list endpoint returns totalSuggestions, assignedCount, aggregatedNotFoundCount per run
- UI: show Total/Matched/Not found columns using fresh aggregates
- Add anchor link Run #ID and wording 'Pairs created in this run'

backend/prisma/migrations/20251130122800_add_origin_run_id_to_suggestions/migration.sql

@@ -0,0 +1,13 @@
+-- Add origin_run_id column to recording_suggestions
+ALTER TABLE "recording_suggestions" ADD COLUMN "origin_run_id" INTEGER;
+
+-- Add foreign key to matching_runs
+ALTER TABLE "recording_suggestions"
+  ADD CONSTRAINT "recording_suggestions_origin_run_id_fkey"
+  FOREIGN KEY ("origin_run_id") REFERENCES "matching_runs"("id")
+  ON DELETE SET NULL ON UPDATE CASCADE;
+
+-- Simple index to support joins by origin_run_id
+CREATE INDEX IF NOT EXISTS "recording_suggestions_origin_run_id_idx"
+  ON "recording_suggestions"("origin_run_id");
+

backend/src/routes/admin.js

@@ -104,6 +104,30 @@ router.get('/events/:slug/matching-runs', authenticate, async (req, res, next) =
       },
     });
 
+    // Aggregate fresh stats per run from recording_suggestions (origin_run_id)
+    // Cheap and valuable: shows actual created pairs in this run.
+    if (runs.length > 0) {
+      const runIds = runs.map(r => r.id);
+      // Single SQL query for all listed runs
+      const placeholders = runIds.join(',');
+      const aggRows = await prisma.$queryRawUnsafe(
+        `SELECT origin_run_id AS "originRunId",
+                COUNT(*)::int AS "totalSuggestions",
+                COUNT(*) FILTER (WHERE recorder_id IS NOT NULL)::int AS "assignedCount",
+                COUNT(*) FILTER (WHERE status = 'not_found')::int AS "notFoundCount"
+         FROM recording_suggestions
+         WHERE event_id = ${event.id} AND origin_run_id IN (${placeholders})
+         GROUP BY origin_run_id`
+      );
+      const aggByRun = new Map(aggRows.map(r => [r.originRunId, r]));
+      for (const r of runs) {
+        const agg = aggByRun.get(r.id) || { totalSuggestions: 0, assignedCount: 0, notFoundCount: 0 };
+        r.totalSuggestions = agg.totalSuggestions;
+        r.assignedCount = agg.assignedCount;
+        r.aggregatedNotFoundCount = agg.notFoundCount; // keep original notFoundCount for backward compat
+      }
+    }
+
     res.json({ success: true, count: runs.length, data: runs });
   } catch (error) {
     next(error);