refactor: scrub residual ScadaLink refs → ScadaBridge (env vars, config keys, assembly name, SQL login)

Renames the 13 SCADALINK_* runtime env vars → SCADABRIDGE_*, the ScadaLink__
.NET config keys → ScadaBridge__, the stale ScadaLink.Host.exe assembly name
→ ZB.MOM.WW.ScadaBridge.Host.exe, the scadalink_app SQL login → scadabridge_app,
and residual identifiers/comments/docs. Migration records (prior rename
tooling/design, DB-rename helper, this scrub script) carved out.

Adds tools/scrub-scadalink-refs.sh.

tests/ZB.MOM.WW.ScadaBridge.PerformanceTests/AuditLog/HotPathLatencyTests.cs

@@ -110,10 +110,10 @@ public class HotPathLatencyTests
         var p95Us = MeasureP95Microseconds(MeasureIterations, () => _ = filter.Apply(evt));
 
         // Default budget 50 µs (spec target). Override via env for slow CI:
-        // SCADALINK_AUDIT_FILTER_4KB_P95_US — interpret as the regression
+        // SCADABRIDGE_AUDIT_FILTER_4KB_P95_US — interpret as the regression
         // guard threshold. Print the observed value so a missed budget gives
         // useful telemetry on the test output.
-        var threshold = GetThresholdMicroseconds("SCADALINK_AUDIT_FILTER_4KB_P95_US", 50d);
+        var threshold = GetThresholdMicroseconds("SCADABRIDGE_AUDIT_FILTER_4KB_P95_US", 50d);
         Assert.True(p95Us < threshold,
             $"4KB body filter p95 = {p95Us:F1} µs; threshold = {threshold:F1} µs");
     }
@@ -137,7 +137,7 @@ public class HotPathLatencyTests
 
         var p95Us = MeasureP95Microseconds(MeasureIterations, () => _ = filter.Apply(evt));
 
-        var threshold = GetThresholdMicroseconds("SCADALINK_AUDIT_FILTER_RAW_P95_US", 10d);
+        var threshold = GetThresholdMicroseconds("SCADABRIDGE_AUDIT_FILTER_RAW_P95_US", 10d);
         Assert.True(p95Us < threshold,
             $"Raw-event filter p95 = {p95Us:F1} µs; threshold = {threshold:F1} µs");
     }