fix(security): close Theme 7 — 8 secrets / redaction / append-only findings

Security-sensitive batch, handled main-thread for careful judgment on
secret-leak and pepper-bypass paths.

Secret leak / pepper bypass:
- CD-016 (pepper bypass): InboundApiRepository's GetApiKeyByValueAsync no
  longer hashes the candidate with the unpeppered ApiKeyHasher.Default —
  ctor takes a lazy Func<IApiKeyHasher> accessor (lazy so test composition
  roots without a pepper still bring up the repository), and the DI
  registration wires sp.GetService<IApiKeyHasher>() so the production
  peppered hasher matches the stored KeyHash. Regression test asserts
  positive (peppered roundtrip) AND negative (Default hasher misses the
  same key — proving the lookup uses the injected hasher).
- MgmtSvc-020 (SMTP credential leak): UpdateSmtpConfig/ListSmtpConfigs
  now project through SmtpConfigPublicShape so the response payload and
  audit-row afterState never carry the Credentials field — only a
  HasCredentials bool. The SMTP password / OAuth2 client secret no
  longer leaves the Admin-only UpdateSmtpConfig boundary the caller
  already supplied it to.

Redaction:
- AuditLog-008 (test-fixture under-redact): new
  SafeDefaultAuditPayloadFilter (stateless singleton) does HTTP header
  redaction for the always-sensitive defaults (Authorization, X-Api-Key,
  Cookie, Set-Cookie). FallbackAuditWriter, CentralAuditWriter, and
  AuditLogIngestActor (both ingest paths) default to it instead of null
  — composition roots that bypass AddAuditLog can no longer write
  unredacted auth headers to the audit store.
- NotifService-025 (over-mask): CredentialRedactor.Scrub now only masks
  the last colon-separated component (password / clientSecret) AND only
  if it's >= 12 chars (typical password heuristic). Short user names
  like "root" no longer become global redaction tokens that eat unrelated
  diagnostic text. The full packed string is always masked regardless of
  length. 3 new negative tests pin the no-over-mask contract.

Audit-row correctness / fail-loud:
- InboundAPI-025: Program.cs UseWhen predicate now excludes /api/audit,
  /api/management, /api/centralui, /api/script-analysis AND requires POST
  — the AuditWriteMiddleware no longer emits spurious ApiInbound rows
  for audit-log query/export endpoints (write-on-read recursion broken).
- ESG-021: ApplyAuth now logs Warning (not silent) on empty
  AuthConfiguration for apikey/basic, unknown AuthType, and malformed
  Basic config. AuthConfiguration value NEVER logged. AuthType=none
  remains silent (documented unauthenticated sentinel).
- Security-021: AddSecurity now logs a startup Warning when
  RequireHttpsCookie=false — an HTTP-only deployment that previously
  transmitted the cookie-embedded JWT silently in cleartext is now
  audible in the log.

Defensive:
- CD-021: SwitchOutPartitionAsync's monthBoundary format string now
  yyyy-MM-dd HH:mm:ss.fffffff (datetime2(7) precision) so a future
  sub-second / non-midnight boundary doesn't silently round to the
  wrong partition.

Plus reconciled stale per-module Open-findings counters that had drifted
from earlier sessions (AuditLog, CD, ESG, IAPI, MgmtSvc, NotifService,
Security).

Build clean; all affected test projects green (Host 208, ConfigDB 242,
ESG 69, IAPI 151, MgmtSvc 100, NotifService 55, Security 85, AuditLog
247/248 — 1 pre-existing date-sensitive integration test flake on
PartitionPurgeTests, unrelated). README regenerated: 46 open (was 54).

src/ScadaLink.ConfigurationDatabase/ServiceCollectionExtensions.cs

@@ -1,6 +1,7 @@
 using Microsoft.AspNetCore.DataProtection;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using ScadaLink.Commons.Interfaces;
 using ScadaLink.Commons.Interfaces.Repositories;
 using ScadaLink.Commons.Interfaces.Services;
@@ -53,7 +54,15 @@ public static class ServiceCollectionExtensions
         services.AddScoped<INotificationOutboxRepository, NotificationOutboxRepository>();
         services.AddScoped<IAuditLogRepository, AuditLogRepository>();
         services.AddScoped<ISiteCallAuditRepository, SiteCallAuditRepository>();
-        services.AddScoped<IInboundApiRepository, InboundApiRepository>();
+        // CD-016: factory registration wires a lazy accessor for IApiKeyHasher so
+        // the production peppered hasher is used (via DI) when GetApiKeyByValueAsync
+        // is actually called, but composition roots that never call it (and may
+        // not register IApiKeyHasher at all) still bring up the repository.
+        services.AddScoped<IInboundApiRepository>(sp => new InboundApiRepository(
+            sp.GetRequiredService<ScadaLinkDbContext>(),
+            hasherAccessor: () => sp.GetService<Commons.Types.InboundApi.IApiKeyHasher>()
+                ?? Commons.Types.InboundApi.ApiKeyHasher.Default,
+            logger: sp.GetService<ILogger<InboundApiRepository>>()));
         services.AddScoped<IAuditCorrelationContext, AuditCorrelationContext>();
         services.AddScoped<IAuditService, AuditService>();
         services.AddScoped<IInstanceLocator, InstanceLocator>();