feat(telemetry): AddZbSerilog minimum-level governance hook; bump to 0.2.0 (scadaproj#12)

Adds an additive AddZbSerilog(builder, configure, configureSerilog) overload
taking ZbSerilogOptions:
- MinimumLevelGovernor: Func<IConfiguration, LogEventLevel?> applied with
  MinimumLevel.Is AFTER ReadFrom.Configuration, so an app-owned key (e.g.
  ScadaBridge:Logging:MinimumLevel) outranks Serilog:MinimumLevel; null defers
  to config; Serilog:MinimumLevel:Override:* entries still apply.
- ConfigureLogger: runs last, for app filters/enrichers/sinks (ScadaBridge's
  standby active-node exclusion).

The two-argument overload is unchanged. 8 new tests (4 fail with the hook
neutralized). Telemetry + Telemetry.Serilog 0.1.0 -> 0.2.0, not published.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

components/observability/GAPS.md

@@ -230,7 +230,10 @@ sister apps in one pass, behaviour-preserving. Each adoption landed on a per-rep
   precedence and silently drop the knob. So ScadaBridge keeps the factory and only **adds the shared
   `TraceContextEnricher`** to it — gaining trace↔log correlation without regressing the contract. Full
   `AddZbSerilog` adoption for ScadaBridge would first require teaching the shared bootstrap to accept a
-  caller-supplied minimum-level governance hook (→ #12).
+  caller-supplied minimum-level governance hook (→ #12). **Library half landed in Telemetry `0.2.0` (unpublished, 2026-11-09):** `AddZbSerilog(builder,
+  configure, s => { s.MinimumLevelGovernor = …; s.ConfigureLogger = …; })` — the governor runs after
+  `ReadFrom.Configuration`, `ConfigureLogger` carries the standby `active-node` filter. ScadaBridge's switch is
+  the remaining follow-on in that repo.
 - **MxGateway keeps `GatewayLogScope` + request-logging middleware as-is.** The Serilog MEL provider
   captures MEL `BeginScope` dictionaries as structured properties, so the scope/correlation code keeps
   producing the same properties under Serilog. Only the provider swap + the `ILogRedactor` adapter were