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");
+