over-engineering audit: remove dead code, speculative config, duplicate queues

- delete embedded community resolver snapshot (6,760 lines) + EmbeddedServers +
  DNS_SERVERS=fresh; curated resolvers are the default. Simplify Warm (no
  sampling).
- one generic internal/sample.Queue[T] replaces three near-identical
  random-sample queues (probe, pipeline, discover).
- delete unreachable index.listOpenSearch (OpenSearch is never listable).
- delete classifyCloudFront (its match is always discarded, !ResourceSpecific).
- delete probe.Probe wrapper + Describe; tests use ProbeDetailed.
- delete store.Pool(), model.SourceDNSAlias, discover.QueueLen.
- drop dead config/no-op knobs: pipeline DirectWorkers, discover MaxPerDomain,
  discover S3/GCS/DO flags, BUCKET_SCAN_DO.
~-7,000 lines (mostly the resolver snapshot), 0 deps removed, tests green.

internal/index/index.go

@@ -55,8 +55,6 @@ func (x *Indexer) List(ctx context.Context, c model.Candidate) ([]model.Entry, e
 		switch c.Service {
 		case model.ServiceS3:
 			return x.listS3(ctx, c.Hostname)
-		case model.ServiceOpenSearch:
-			return x.listOpenSearch(ctx, c.Hostname)
 		}
 	case model.ProviderGCP:
 		switch c.Service {
@@ -360,36 +358,6 @@ func (x *Indexer) listFirebase(ctx context.Context, host string) ([]model.Entry,
 	return entries, nil
 }
 
-// --- OpenSearch / Elasticsearch indices ---
-
-func (x *Indexer) listOpenSearch(ctx context.Context, host string) ([]model.Entry, error) {
-	resp, err := x.get(ctx, x.scheme+"://"+host+"/_cat/indices?format=json&h=index,health,status,docs.count,store.size")
-	if err != nil {
-		return nil, err
-	}
-	var rows []struct {
-		Index    string `json:"index"`
-		Health   string `json:"health"`
-		Status   string `json:"status"`
-		Docs     string `json:"docs.count"`
-		StoreSiz string `json:"store.size"`
-	}
-	err = json.NewDecoder(io.LimitReader(resp.Body, 8<<20)).Decode(&rows)
-	resp.Body.Close()
-	if err != nil {
-		return nil, err
-	}
-	var entries []model.Entry
-	for _, r := range rows {
-		size, _ := strconv.ParseInt(strings.TrimSuffix(r.Docs, " "), 10, 64)
-		entries = append(entries, model.Entry{Kind: "index", Name: r.Index, Size: size, ETag: r.StoreSiz})
-		if len(entries) >= x.maxObjects {
-			break
-		}
-	}
-	return entries, nil
-}
-
 func parseTime(s string) time.Time {
 	if s == "" {
 		return time.Time{}

internal/index/index_test.go

@@ -81,19 +81,6 @@ func TestListFirebase(t *testing.T) {
 	}
 }
 
-func TestListOpenSearch(t *testing.T) {
-	x, host := newTestIndexer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		_, _ = w.Write([]byte(`[{"index":"logs-2024","docs.count":"100","store.size":"1.2mb"}]`))
-	}))
-	entries, err := x.List(context.Background(), model.Candidate{Hostname: host, Provider: model.ProviderAWS, Service: model.ServiceOpenSearch})
-	if err != nil {
-		t.Fatal(err)
-	}
-	if len(entries) != 1 || entries[0].Name != "logs-2024" || entries[0].Size != 100 {
-		t.Fatalf("unexpected entries: %+v", entries)
-	}
-}
-
 func TestListBounded(t *testing.T) {
 	var keys strings.Builder
 	for i := 0; i < 100; i++ {