fix(auditlog)+fix(configdb): budget the ingest fallback loop; index + varchar-type the SiteCalls list query (arch-review 2026-08-19 P5-1 + P5-2)

P5-1: AuditLogIngestActor.OnCachedTelemetryAsync's per-entry fallback loop
(used when the cached-telemetry batch fast path fails) ran with no
budget/cancellation, unlike OnIngestAsync's fallback. A slow/wedged DB could
freeze the central ingest singleton's mailbox for minutes. The loop now runs
under its own fresh IngestFallbackBudget CancellationTokenSource (mirroring
OnIngestAsync), passes the token into BeginTransactionAsync/
InsertIfNotExistsAsync/UpsertAsync, and stops early on budget exhaustion,
logging how many entries were left for the periodic reconciliation pull to
pick up.

P5-2: SiteCallAuditRepository.QueryAsync ordered by
(CreatedAtUtc DESC, TrackedOperationId DESC) with no index leading
unconditionally on CreatedAtUtc, forcing a full scan+sort on an unfiltered
page. Added IX_SiteCalls_Created_TrackedOperationId (migration
AddSiteCallsListSortIndex + matching hand-written production-parity script
under docs/plans/sql/). Also switched the query from FromSqlInterpolated
(which binds string filters as nvarchar(4000)) to FromSqlRaw with explicitly
SqlDbType.VarChar-typed parameters, matching the SiteCalls columns'
IsUnicode(false) declaration and the write path's existing Param(...)
pattern, so seeks — including the keyset predicate — are no longer blocked
by an implicit conversion.

Tests: new AuditLogIngestActorCombinedTelemetryTests case proves the
fallback budget bounds the wait (hanging repo stub, ~5s not indefinite),
that remaining entries are skipped, and that a non-default/cancellable
token reaches the repository call; verified fail-unfixed by reverting the
actor change (test times out at its 20s bound). Existing
SiteCallAuditRepositoryTests QueryAsync/keyset/stuck-cutoff cases (real
MSSQL) confirm the raw-SQL rewrite still returns correct pages.

src/ZB.MOM.WW.ScadaBridge.ConfigurationDatabase/Migrations/ScadaBridgeDbContextModelSnapshot.cs

@@ -171,6 +171,10 @@ namespace ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.Migrations
                         .HasDatabaseName("IX_SiteCalls_Terminal")
                         .HasFilter("[TerminalAtUtc] IS NOT NULL");
 
+                    b.HasIndex("CreatedAtUtc", "TrackedOperationId")
+                        .IsDescending()
+                        .HasDatabaseName("IX_SiteCalls_Created_TrackedOperationId");
+
                     b.HasIndex("SourceSite", "CreatedAtUtc")
                         .IsDescending(false, true)
                         .HasDatabaseName("IX_SiteCalls_Source_Created");