refactor(runtime): delete the dead in-place ApplyDelta seam; config change = respawn only (#665)

Since #516 a DriverConfig change is stop + respawn, so DriverSpawnPlan.ToApplyDelta
was always empty and the in-place path had no producer. #663 and #664 were both
latent bugs in it. This deletes it:
- host: ApplyChildDelta, _pendingDelta, HandleApplyResult and HandleDeltaApplied
- plan: DriverSpawnPlan.ToApplyDelta
- actor: the ApplyDelta, ApplyResult and DeltaApplied messages, the Connected
  reinit handler and the mid-connect AdoptConfigDuringInit
- tests: the actor tests that drove the seam

IDriver.ReinitializeAsync and each driver's implementation and unit tests stay.
Comments and docs that cited AdoptConfigDuringInit as the reason a driver must
release prior state at init now cite the IDriver contract and overlapping
retries, which still apply.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

tests/Server/ZB.MOM.WW.OtOpcUa.Runtime.Tests/Drivers/CalculationDependencyFlowTests.cs

@@ -31,7 +31,7 @@ public sealed class CalculationDependencyFlowTests : RuntimeActorTestBase
         return new RawTagEntry(rawPath, json, WriteIdempotent: false);
     }
 
-    /// <summary>Build the merged DriverConfig JSON the ApplyDelta path re-binds from (mirrors the deploy
+    /// <summary>Build the merged DriverConfig JSON an in-place re-bind reads (mirrors the deploy
     /// artifact folding the driver's RawTags into DriverInstanceSpec.DriverConfig).</summary>
     private static string ConfigJson(params RawTagEntry[] tags) =>
         System.Text.Json.JsonSerializer.Serialize(new { rawTags = tags });
@@ -130,7 +130,7 @@ public sealed class CalculationDependencyFlowTests : RuntimeActorTestBase
             published.ShouldContain(e => e.FullReference == "calc/remove" && Equals(e.Snapshot.Value, 7.0));
         }, PresenceBudget, TimeSpan.FromMilliseconds(100));
 
-        // ---- REDEPLOY (in-place ApplyDelta) ----
+        // ---- IN-PLACE RE-BIND (driver ReinitializeAsync) ----
         // New authored set: "keep" script EDITED to src/a*1000; "add" is a NEW tag reading a NEW dep src/b;
         // "remove" is dropped entirely.
         var newConfig = ConfigJson(
@@ -141,8 +141,9 @@ public sealed class CalculationDependencyFlowTests : RuntimeActorTestBase
         // The rebuilt dependency-ref set reflects the NEW authored tags (src/a from keep, src/b from add).
         driver.DependencyRefs.OrderBy(r => r).ShouldBe(new[] { "src/a", "src/b" });
 
-        // Part 2 sequencing: the host re-registers the adapter AFTER reinit (DeltaApplied → HandleDeltaApplied).
-        // Mirror that here — re-register so the adapter adopts the NEW ref set (incl. the brand-new src/b).
+        // The adapter re-reads the driver's refs only when told to; re-register AFTER the reinit so it adopts the
+        // NEW ref set (incl. the brand-new src/b). (The runtime respawns on a config change, #665, so a fresh
+        // adapter registers the new set in PreStart; this exercises the driver + adapter contract directly.)
         adapter.Tell(new DependencyConsumerMuxAdapter.ReRegister());
 
         // Leg 2 — after redeploy: the NEW dep src/b flows + the NEW tag computes; the EDITED script serves the