Merge b626-630 (batch #626+): release prior device/session state on re-Initialize in six drivers

Conflict in S7Driver.ReleaseConnectionAsync resolved: kept the gated Plc swap from #630 and
carried the negotiated-PDU reset from #632 #294 into it.

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

docs/DriverLifecycle.md

@@ -425,6 +425,15 @@ re-entered this path; the watchdog makes it automatic and unbounded, so a device
 have leaked ~360 transports at the 10 s retry interval. The shutdown is best-effort: a driver that throws
 on it still gets its initialise attempt.
 
+**`InitializeAsync` itself releases the previous device/connection state first (#630).** The retry above is not
+the only way in: `DriverInstanceActor.AdoptConfigDuringInit` calls `InitializeAsync` on a live driver with *no*
+teardown, so a driver that does `_devices[host] = new DeviceState(...)` (or `Session = ...`, `Plc = ...`) orphans
+the previous state's probe / recycle / fixed-tree loops and its client. FOCAS, AbLegacy, AbCip, TwinCAT, S7 and
+OpcUaClient now cancel, bounded-join (5 s) and dispose that state at the top of `InitializeAsync`
+(`ReleaseDeviceStatesAsync` / `ReleaseConnectionAsync` / `ReleaseSessionAsync`), alongside Modbus and MQTT.
+It is deliberately the device-state half of `ShutdownAsync` only: the poll engine and subscriptions are *not*
+dropped: the release is scoped to device state so it cannot take state the shutdown path owns. The actor re-subscribes values and alarms after every successful init, so driver-side subscriptions kept across a no-teardown re-init are retained leftovers, not needed for data flow. A new driver must do the same.
+
 #### The fan-out that watchdog triggers: indexed per driver, and one batch
 
 `DisconnectObserved` raises `ConnectivityChanged`, and `DriverHostActor` answers it by pushing