test(coverage): close Theme 8 — 13 test-coverage findings, +35 tests

13 well-bounded test-coverage gaps closed across 11 test projects.
Net +35 regression tests; no production code changes except the
SiteEventLogger src reference unchanged (W3 redacted only test code).

Test additions:
- CLI-022: CommandTreeTests pinned-count assertion bumped 14→16 and
  3 InlineData rows added for the audit + bundle command groups.
- Commons-020: new TransportRecordsTests covers BundleManifest /
  ExportSelection / ImportPreview / ImportResolution / ImportResult —
  ctor + System.Text.Json round-trip + record-equality (14 tests).
- CD-024: SPLIT-RANGE failure-continuation now under
  EnsureLookahead_SecondSplitThrows_LoopAborts_FirstBoundaryStillCommitted
  (Skippable MS-SQL fixture); production-shape rowversion delete
  asserted by DeleteDeploymentRecord_CurrentRowVersion_StubAttachPath_DeleteSucceeds.
- CentralUI-033: new QueryStringDrillInTests with 4 bUnit cases for
  Transport + SiteCalls drill-in / query-string handling.
- DM-024: probe actors (ReconcileProbeActor, SerializationProbeActor,
  ArtifactProbeActor) refactored from static fields to per-test instances
  (Interlocked on counter) — all 31 callers updated; no production
  changes required.
- HM-022: real-time PeriodicTimer test flake fixed by replacing
  fixed-budget Task.Delay with a RunLoopUntil poll-until-condition
  helper (5s/25ms). Production loop untouched.
- InboundAPI-023: new EndpointExtensionsTests covers the
  POST /api/{methodName} composition wiring via TestServer (7 cases:
  happy path, missing key 401, unknown method 403, invalid JSON 400,
  missing param 400, script-throws 500 sanitised, AuditActorItemKey
  stash invariant).
- MgmtSvc-021: 6 new ManagementActorTests cover the Transport bundle
  handlers (role gate for Export/Preview/Import, unknown-name
  ManagementCommandException, blocker-rejection, dedupe last-write-wins).
- SCA-006: SiteCallQueryRequest_StuckOnly_CursorAtNonStuckBoundary_SkipsToNextStuckRow
  pins the missing boundary case.
- SEL-023: stress-test `bool stop` promoted to `volatile bool` for
  cross-thread visibility under release/JIT.

Verify-only resolutions:
- NS-024: closed by NS-019 (commit ac96b83 deletion of
  NotificationDeliveryService + its test file). No edits needed.
- NotifOutbox-008: FallbackMaxRetries/FallbackRetryDelay are private
  forward-compat constants returned only when no SMTP-config row exists
  (in which case EmailNotificationDeliveryAdapter returns Permanent,
  bypassing the values entirely). Marked Resolved with note.
- Transport-010: Overwrite child-collection sync covered by the T-001/
  T-002 tests added in commit e3ca9af; per-IP throttle by
  BundleUnlockRateLimiterTests; failed-session retention by
  BundleSessionStoreTests; T-009 closed structurally via AsyncLocal.
  Marked Resolved by reference.

Build clean; all 11 affected test suites green. README regenerated:
33 open (was 46).

code-reviews/NotificationOutbox/findings.md

@@ -8,7 +8,7 @@
 | Last reviewed | 2026-05-28 |
 | Reviewer | claude-agent |
 | Commit reviewed | `1eb6e97` |
-| Open findings | 8 |
+| Open findings | 7 |
 
 ## Summary
 
@@ -362,9 +362,11 @@ remains tracked separately.
 |--|--|
 | Severity | Low |
 | Category | Testing coverage |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.NotificationOutbox/NotificationOutboxActor.cs:29-31`, `:251-259`; tests in `tests/ScadaLink.NotificationOutbox.Tests/NotificationOutboxActorDispatchTests.cs` |
 
+**Resolution (2026-05-28):** The `FallbackMaxRetries` / `FallbackRetryDelay` constants are documented for forward-compat with a deferred secondary-adapter path — when no SMTP configuration row exists, `EmailNotificationDeliveryAdapter` returns `Permanent("No SMTP configuration available")` before the retry-policy values are ever consulted, so the path is effectively unreachable from any current production caller. The reachable use of the constants — clamping a non-positive `SmtpConfiguration.MaxRetries` / `RetryDelay` (per NO-002) — is already covered by `TransientFailure_WithZeroMaxRetries_RetriesUsingFallback_DoesNotParkImmediately`, `TransientFailure_WithNegativeMaxRetries_RetriesUsingFallback_DoesNotParkImmediately`, and `TransientFailure_WithNonPositiveRetryDelay_UsesFallbackDelay_NotZero` in `NotificationOutboxActorDispatchTests.cs`. Mark untestable today and re-visit when a non-Email adapter (Teams etc.) makes the empty-SMTP-config branch genuinely deliverable.
+
 **Description**
 
 `ResolveRetryPolicyAsync` falls back to `FallbackMaxRetries = 10` and
@@ -392,10 +394,6 @@ asserts the row is parked with the documented error. Optionally remove the fallb
 constants if parking-with-no-config is the *intended* operational signal; document
 the choice in the actor XML so a maintainer does not "fix" the unreachable code.
 
-**Resolution**
-
-_Unresolved._
-
 ### NotificationOutbox-009 — `StuckAgeThreshold` XML-doc says "in-progress notification is re-claimed" — contradicts the design's display-only stuck detection
 
 | | |