chore(localdb): phase-2 DoD sweep

Build: 0 errors solution-wide, and 0 warnings from every project this branch
touches. The ~816 solution-wide warnings are pre-existing xUnit1051 /
OTOPCUA0001 / CS86xx in untouched driver + client test projects.

Tests: full solution run compared against a full run on a detached worktree at
the pre-branch baseline 2e46d054. The two failure SETS are identical -- all 13
tests, same names, zero new failures. Net +26 tests: +3 Core.AlarmHistorian
(drain gate), +6 Runtime (role view), +17 Host.IntegrationTests (migrator +
convergence). Set comparison rather than counts, because the suite carries
standing environment- and load-dependent failures a count would hide.

The greps found real drift Task 6 missed -- eight live sites still naming the
deleted SqliteStoreAndForwardSink, including the AdminUI /alarms/historian
panel text, which is user-visible, and a <see cref> in HistorianAdapterActor
that resolved to nothing without warning. All repointed at
LocalDbStoreAndForwardSink; CLAUDE.md's alarm-history paragraph now also
records the LocalDb buffer and the primary-gated drain, and drops DatabasePath
from the knob list. docs/AlarmTracking.md still promised an
AlarmHistorianOptions.Validate() startup warning for a relative DatabasePath
and an empty SharedSecret; both branches are gone, so it now says so.

Code references to AlarmHistorian:DatabasePath reduce to exactly two intentional
ones: AlarmSfLegacyMigrator.LegacyPathKey and its test. No `new SqliteConnection`
remains anywhere in Core.AlarmHistorian.

Recon doc gains the durable verification record: guard-deletion evidence for
both vacuous passes, the two exact-set replicated-table pins (both assert set
equality, so an added or a dropped registration fails), and the baseline test
comparison with a per-failure account of why each of the 13 is not this
branch's.

Stops here per the plan. Task 8's live gate needs explicit go-ahead; nothing on
this branch is to be merged.

Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW

docs/AlarmTracking.md

@@ -383,8 +383,9 @@ AB CIP ALMD) route to AVEVA Historian via the HistorianGateway:
   capacity, and dead-letter retention are tunable via the `AlarmHistorian`
   config section (`DrainIntervalSeconds`, `Capacity`,
   `DeadLetterRetentionDays`); `AlarmHistorianOptions.Validate()` logs a
-  startup warning for an empty `SharedSecret`, a relative `DatabasePath`,
-  or a non-positive knob.
+  startup warning for a non-positive knob. (It no longer warns about
+  `SharedSecret` or `DatabasePath` — both keys are gone: the connection
+  comes from `ServerHistorian`, and the queue lives in the LocalDb.)
 - `HistorianAdapterActor`
   (`src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/HistorianAdapterActor.cs`)
   subscribes to the cluster `alerts` DPS topic, translates each