test(localdb): port store-and-forward replication intents as CDC convergence specs

Task 10. Specifications first, deletion second: the bespoke ReplicationService
(explicit Add/Remove/Park/Requeue over Akka) dies at Task 14, so its behaviour
is restated here as outcomes the CDC replacement must still deliver. Written
in terms of ROWS, not operations — under CDC there is no Add or Park message to
observe, only a row that must end up right on both nodes.

Not ported: ReplicationOperations_AreDispatchedInIssueOrder. It asserts the
mechanism (inline fire-and-forget dispatch), and CDC capture is asynchronous
and batched by construction. Its portable content is the ordering OUTCOME —
add-then-remove must never converge to present — which is a test here, with
that reasoning recorded in the file so it does not read as an accidental drop.

DEVIATION: extracted the Phase 1 fixture into LocalDbSitePairHarness rather
than duplicating ~150 lines. Phase 1's tests now derive from it and still pass
unchanged. The harness registers the Phase 2 tables itself, since production
OnReady does not until Task 14; that method is marked for deletion at the
cutover, and the 8-table list is written literally so a cutover registering the
wrong set fails these tests instead of agreeing with itself.

Non-vacuity verified by unregistering sf_messages: 6 of 7 failed. The 7th —
the ordering test — PASSED, because an absent row is also what a pair that
replicates nothing looks like. Fixed with a control row that must converge in
the same window, so the absence is evidence rather than silence.

Also corrected two comments from Task 9 that claimed Task 14 makes
notification_lists/smtp_configurations replicated. It explicitly does not
register them, for the same reason the migrator skips them.

Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts

tests/ZB.MOM.WW.ScadaBridge.Host.Tests/SiteLocalDbLegacyMigratorTests.cs

@@ -465,9 +465,10 @@ public class SiteLocalDbLegacyMigratorTests : IDisposable
     {
         // smtp_configurations.password is PLAINTEXT. Both tables are purged on every deploy
         // and permanently empty by design since the site write paths were removed
-        // (2026-07-10), but a pre-fix legacy file can still hold rows — and Task 14 makes
-        // these tables REPLICATED. Migrating them would push plaintext SMTP passwords across
-        // a replication channel whose only historical payload was exactly that.
+        // (2026-07-10), but a pre-fix legacy file can still hold rows. The cutover also
+        // declines to REGISTER these two for replication, for the same reason — so migrating
+        // them would leave plaintext SMTP passwords in the consolidated database, one future
+        // RegisterReplicated away from being shipped to a peer, for config nothing reads.
         var sitePath = Path_("scadabridge.db");
         SeedLegacySiteStorage(sitePath);
         var config = Config(siteDbPath: sitePath);