fix(dcl): robust static-tag seeding — bounded-retry+log initial seed (#1) and re-seed on reconnect (#3)

STATIC tags (no further OnDataChange after advise) depend entirely on the
seed read. Pre-fix HandleSubscribe seeded only on Success && Value != null,
silently dropping a seed that raced the just-created advise (VT_EMPTY) — so a
static tag stayed Uncertain forever while the source read Good. ReSubscribeAll
did no seeding at all, so a static tag could not self-heal across reconnect.

- New SeedTagsAsync helper: per-tag ReadAsync (not a bulk read — some gateways
  time out on large batches) with round-based bounded retry
  (SeedReadMaxAttempts/SeedReadRetryDelay), logging any tag that never yields a
  value (named — previously zero log trace).
- HandleSubscribe seed loop delegates to SeedTagsAsync.
- ReSubscribeAll re-seeds re-advised tags after reconnect via the
  generation-guarded TagValueReceived path (fan-out keys off
  _subscriptionsByInstance, preserved across reconnect).

Diagnosed live on wonder-app-vd03 2026-06-17 (see scadabridge-dcl-static-tag-false-bad).
Mechanism #2 (single transient-bad push) left as a follow-up.

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/DataConnectionOptions.cs

@@ -20,4 +20,24 @@ public class DataConnectionOptions
     /// disconnect toward the failover retry count (DataConnectionLayer-009).
     /// </summary>
     public TimeSpan StableConnectionThreshold { get; set; } = TimeSpan.FromSeconds(60);
+
+    /// <summary>
+    /// DataConnectionLayer-027: total number of attempts the seed read makes per tag
+    /// before giving up. The initial subscribe seed (and the reconnect re-seed) reads
+    /// each just-advised tag to capture its current value; on a cold/fresh advise the
+    /// read can race the subscription and return an empty/failed result. A STATIC tag
+    /// (one that never fires another OnDataChange) would then stay Uncertain forever,
+    /// because its bridge value depends entirely on that seed. Re-reading the still-empty
+    /// subset a bounded number of times lets the advise warm up. Minimum 1 (1 = single
+    /// read, no retry).
+    /// </summary>
+    public int SeedReadMaxAttempts { get; set; } = 3;
+
+    /// <summary>
+    /// DataConnectionLayer-027: delay between seed-read attempts for the tags that have
+    /// not yet returned a usable value. Applied once per round across the whole pending
+    /// subset, so the total added latency is bounded to
+    /// <c>(SeedReadMaxAttempts - 1) × SeedReadRetryDelay</c> regardless of tag count.
+    /// </summary>
+    public TimeSpan SeedReadRetryDelay { get; set; } = TimeSpan.FromMilliseconds(250);
 }