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

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Calculation/CalculationDriver.cs

@@ -67,7 +67,7 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
 
     // Authored calc tags, keyed by RawPath (identity + evaluation id). Built at construction so
     // DependencyRefs is available BEFORE InitializeAsync (the host reads it when spawning the mux-adapter),
-    // and REBUILT on every ReinitializeAsync (an in-place ApplyDelta re-binds an edited calc-tag set).
+    // and REBUILT on every ReinitializeAsync / body-carrying InitializeAsync (an in-place re-bind of an edited calc-tag set).
     private readonly Dictionary<string, CalculationTagDefinition> _tagsByRawPath = new(StringComparer.Ordinal);
 
     // rawPath (a dependency) → the calc tags that read it AND are change-triggered. Drives OnDependencyValue.
@@ -139,7 +139,7 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
     ///     (Re)build the authored tag table (<see cref="_tagsByRawPath"/>), the change-trigger fan-out
     ///     (<see cref="_changeDependents"/>), the dependency-ref interest set (<see cref="_dependencyRefs"/>),
     ///     and the per-tag state map (<see cref="_stateByRawPath"/>) from <paramref name="config"/>. Called
-    ///     once at construction AND on every <see cref="ReinitializeAsync"/> so an in-place ApplyDelta — a
+    ///     once at construction AND on every <see cref="ReinitializeAsync"/> so an in-place config change — a
     ///     calc-tag add/remove/edit, or a script-source edit — actually takes effect. Extracted so the ctor
     ///     and reinit paths share ONE construction routine and cannot drift.
     ///     <para>Per-tag <see cref="TagState"/> is preserved for a tag that survives the edit (cheap last-known
@@ -200,7 +200,7 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
     }
 
     // Reinit config-bind options — mirrors the factory's bind (case-insensitive, enum-string, trailing-comma
-    // tolerant) so an ApplyDelta payload re-binds identically to the spawn payload.
+    // tolerant) so an in-place config payload re-binds identically to the spawn payload.
     private static readonly JsonSerializerOptions ReinitJsonOptions = new()
     {
         PropertyNameCaseInsensitive = true,
@@ -209,8 +209,8 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
         Converters = { new JsonStringEnumConverter() },
     };
 
-    /// <summary>Re-bind the authored raw calc tags from a new merged DriverConfig JSON (the ApplyDelta
-    /// payload). The ctor-fixed <see cref="CalculationEvaluator"/> timeout is kept — <c>RunTimeout</c> is bound
+    /// <summary>Re-bind the authored raw calc tags from a new merged DriverConfig JSON (an in-place
+    /// config payload). The ctor-fixed <see cref="CalculationEvaluator"/> timeout is kept — <c>RunTimeout</c> is bound
     /// at spawn (a change to it is out of this in-place path's scope). A parse failure logs and keeps the
     /// current tags so a malformed delta can never blank the driver.</summary>
     private CalculationDriverOptions ParseOptions(string driverConfigJson)
@@ -287,8 +287,8 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
 
     /// <inheritdoc />
     /// <remarks>
-    ///     #664: <c>InitializeAsync</c> is reachable on a LIVE driver — <c>DriverInstanceActor.AdoptConfigDuringInit</c>
-    ///     re-runs it with a NEW config when an ApplyDelta lands mid-connect — so it adopts a config carrying a
+    ///     #664: <c>InitializeAsync</c> takes a config document and the <see cref="IDriver"/> contract is that the
+    ///     driver serves it (the runtime's mid-connect adoption path was deleted in #665) — so it adopts a config carrying a
     ///     real body (the #516 convention every other driver follows), and disposes any running timer scheduler
     ///     before arming a fresh one (#630: re-initialise without teardown must not leak). A <c>"{}"</c> / empty
     ///     document keeps the constructor-supplied tags, as unit tests rely on.
@@ -308,14 +308,10 @@ public sealed class CalculationDriver : IDriver, IDependencyConsumer, ISubscriba
     /// <inheritdoc />
     public Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
     {
-        // A calc-tag add/remove/edit — or a script edit that changes the injected scriptSource — changes the
-        // merged DriverConfig, which DriverSpawnPlanner routes to an in-place ApplyDelta → THIS call (a
-        // respawn fires only on a DriverType/ResilienceConfig change). So the authored tag table is NOT
-        // fixed at construction: we re-bind the new config and REBUILD the tag table + dependency-ref set
-        // here. Without this, added tags never compute, removed tags keep publishing, and edited scripts
-        // serve stale results (deploy reports success but nothing changed). After the rebuild _dependencyRefs
-        // reflects the new authored tags, and the host re-registers the mux interest post-reinit (the
-        // DriverInstanceActor.DeltaApplied → DriverHostActor path, sequenced AFTER this completes).
+        // An in-place config change: re-bind the new config and REBUILD the tag table + dependency-ref set, so
+        // added tags compute, removed tags stop publishing and edited scripts serve the new result. The runtime
+        // itself applies a DriverConfig change by respawning (#516/#665), where a fresh driver registers its
+        // new dependency refs on construction; this path keeps the IDriver contract honest for any caller.
         StopTimers();
         AdoptConfig(driverConfigJson);
         // Re-arm timers off the rebuilt tag set.