feat(opcuaclient): #676 follow-ups — endpoint rewrite, stall wire test, fast definitive-loss recovery

- Endpoint rewrite: the driver now connects to the configured host AND port (scheme
  match, advertised path kept) instead of the server-advertised URL — fixes NAT/port-map
  upstreams and lets an in-test proxy carry the session (SDK SelectEndpoint rule).
- TcpStallProxy + OpcUaClientDriverStallWireTests: the in-place blip (#670) is now
  wire-tested on loopback — one Bad, frozen read stamp, same session, identical value
  republished Good, a post-recovery change arrives, no source-time regression after
  the SDK's late backlog flush.
- Defect found by that test, fixed: a change published right after a stall rode a
  Publish response the SDK timed out and never republished, leaving the node Good on
  the pre-change value indefinitely. New trailing reconcile read (Timeout +
  KeepAliveInterval after recovery) publishes any Good value newer than the last
  accepted one, through the replay guard's mark.
- IDriverConnectionLossSource (Core.Abstractions): opt-in definitive-loss signal.
  DriverInstanceActor attaches in PreStart / detaches in PostStop and turns a raise
  into a disconnect only while Connected. OpcUaClient raises once per session on
  keep-alive BadSessionIdInvalid/BadSessionClosed/BadSessionNotActivated/
  BadServerHalted (measured: the SDK never re-opens a halted channel) or a dropped
  subscription; ambiguous codes stay with the #527 watchdog.
- Replay guard: one Information summary per recovery when the window closes
  ("dropped N late notifications across M refs"), with a timer so quiet
  subscriptions log it too.
- ReconnectPeriod deleted (options, AdminUI form, docs, tests); stored configs that
  carry reconnectPeriod still parse in the factory, probe and browser.
- Docs: OpcUaClient.md, DriverLifecycle.md, driver-specs.md, CLAUDE.md.

docs/v2/driver-specs.md

@@ -815,7 +815,6 @@ Already used by Client.Shared in the existing codebase.
 | `Password` | string? | — | For Username auth |
 | `SessionTimeoutMs` | int | 120000 | Server-negotiated session timeout |
 | `KeepAliveIntervalMs` | int | 5000 | Session keep-alive interval |
-| `ReconnectPeriodMs` | int | 5000 | Initial reconnect delay |
 | `BrowseStrategy` | enum | Full | `Full` (browse all at startup), `Lazy`, `Hybrid` |
 | `BrowseRoot` | string? | — | Optional root NodeId to mirror (default: ObjectsFolder) |
 | `AutoAcceptCertificates` | bool | false | Accept untrusted server certificates |