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.

cmd/ctcloud/main.go

@@ -108,15 +108,9 @@ func run() error {
 		// of costing a timeout on every random pick.
 		resolver = dns.NewServerPool(dns.CuratedServers())
 		warmCtx, cancel := context.WithTimeout(ctx, 8*time.Second)
-		healthy := resolver.Warm(warmCtx, "example.com", 16, 64)
+		healthy := resolver.Warm(warmCtx, "example.com", 16)
 		cancel()
 		slog.Info("dns resolvers configured", "count", resolver.Len(), "healthy", healthy, "set", "curated")
-	case len(dnsServers) == 1 && dnsServers[0] == "fresh":
-		resolver = dns.NewServerPool(append(dns.CuratedServers(), dns.EmbeddedServers()...))
-		warmCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
-		healthy := resolver.Warm(warmCtx, "example.com", 32, 256)
-		cancel()
-		slog.Info("dns resolvers warmed", "total", resolver.Len(), "healthy", healthy, "set", "fresh")
 	default:
 		resolver = dns.NewServerPool(dnsServers)
 		slog.Info("dns resolvers configured", "count", resolver.Len(), "set", "custom")
@@ -150,9 +144,7 @@ func run() error {
 	if cfg.BucketScanEnabled {
 		discoverer = discover.New(discover.Config{
 			QPS: cfg.BucketScanQPS, Workers: cfg.BucketScanWorkers, Queue: cfg.BucketScanQueue,
-			S3: true, GCS: true, DOSpaces: cfg.BucketScanDO,
-			DORegions: []string{"nyc3", "sfo3", "fra1", "ams3", "sgp1"},
-			Indexer:   indexer, Metrics: m,
+			Indexer: indexer, Metrics: m,
 			OnOpen: func(uctx context.Context, c model.Candidate, detail string, entries []model.Entry) {
 				if _, err := st.EnsureAsset(uctx, c); err != nil {
 					return
@@ -168,7 +160,7 @@ func run() error {
 		})
 		discoverer.Start(ctx)
 		slog.Info("bucket name discovery enabled", "event", "startup",
-			"qps", cfg.BucketScanQPS, "workers", cfg.BucketScanWorkers, "do_spaces", cfg.BucketScanDO)
+			"qps", cfg.BucketScanQPS, "workers", cfg.BucketScanWorkers)
 	}
 
 	var prober *probe.Prober