fix(runtime,adminui): per-tag write ordering, pessimistic init bound, unique generations, PostStop budget (fix round 1)

- Writes: a second write to a tag already inside the driver waits in the
  queue behind it (_tagsInFlight) while other tags still run under the
  cap of 4; queued writes are stamped and failed BadTimeout at dequeue
  once older than the 8 s host Ask budget (Props queuedWriteBudget)
  instead of being written late.
- Initialise attempts are bounded pessimistically (initializeTimeout,
  default 30 s = 2x Tier C) on top of the invoker's token-only timeout:
  an overrun is logged as abandoned, reported InitializeFailed so the
  retry loop continues, and its late result is dropped by generation.
  Generations come from a process-wide Interlocked counter so a prior
  incarnation's late result cannot collide (F6).
- PostStop shares one shutdownTimeout budget across shutdown + dispose.
- TelemetryDialSupervisor cancels the establishment deadline on
  StreamStopped; FleetDiagnosticsClient builds the ActorSelection inside
  the try (a malformed node degrades to "unavailable"); the diagnostics
  page labels the column "Last health publish".
- Tests: same-tag serialisation with a distinct-tag positive control;
  stale queued write BadTimeout; token-ignoring hung init -> later
  attempt connects; stopwatch assertion demoted to a ceiling.

Refs #731

Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/FleetDiagnostics.razor

@@ -120,7 +120,7 @@ else
                             <th>State</th>
                             <th class="numeric">Connected devices</th>
                             <th class="numeric">Faulted devices</th>
-                            <th>Last change</th>
+                            <th title="When the driver child last published a changed health snapshot (its spawn time until the first)">Last health publish</th>
                         </tr>
                     </thead>
                     <tbody>