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

CLAUDE.md

@@ -1161,16 +1161,16 @@ host logger factory (wired in `DriverFactoryBootstrap`; the FOCAS and TwinCAT fa
   first release the prior device/session state (cancel, ≤ 5 s join, dispose — incl. the AbCip alarm projection;
   FOCAS's is PAUSED, its told record kept, #647) — the device-state half of `ShutdownAsync` only; the poll engine is kept and the actor re-subscribes
   after every successful init. AbCip publishes fresh tag tables by reference swap (a second init used to throw
-  "tag name collision" on `AdoptConfigDuringInit`); S7 swaps `Plc` under `_gate`.
+  "tag name collision"); S7 swaps `Plc` under `_gate`.
 - **Data and alarm subscriptions are independent in `DriverInstanceActor` (#662):** a data re-subscribe (every
   deploy's bulk push to a kept driver) detaches DATA only (`DetachDataSubscription`) — it used to unhook
   `OnAlarmEvent` too, silently killing the native-alarm feed until a respawn. The health-poll reconcile
   re-attaches/re-subscribes alarms as well as data, so a failed alarm subscribe is retried every tick.
-  A Connected in-place `ApplyDelta` (unreachable from deploys since #516) releases both subscriptions at the
-  driver, reinitialises, then re-subscribes both (#663) — it used to keep handles the reinit had invalidated.
-  A mid-connect `ApplyDelta` re-runs `InitializeAsync(newConfig)`, so **every driver's `InitializeAsync` must adopt a
-  config with a body** — Calculation now does, Galaxy (no hot-swap) now refuses a non-equivalent one, and the actor
-  sends `DeltaApplied` once the adopted init succeeds (#664).
+- **A config change is a respawn — there is NO in-place path (#665).** The `ApplyDelta`/`ApplyResult`/`DeltaApplied`
+  seam (host `ApplyChildDelta`, `DriverSpawnPlan.ToApplyDelta`, the actor's Connected reinit and mid-connect
+  `AdoptConfigDuringInit`) was unreachable since #516 and is deleted; #663/#664 were latent bugs in it. `IDriver.ReinitializeAsync`
+  stays as a per-driver contract the runtime never calls. Every driver's `InitializeAsync` still serves the config it is
+  handed (Calculation adopts, Galaxy refuses a non-equivalent one — #664), and still releases prior state (#630).
   `docs/DriverLifecycle.md`.
 - **S7 (#632/#638):** STRING/WSTRING/CHAR/WCHAR and DTL/DATE/TOD/TIME/S5TIME codecs (`S7ValueCodecs`; TOD/TIME/S5TIME
   surface as Int32 ms); an undecodable buffer or unrepresentable write is `BadOutOfRange` with no health impact.