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/plans/2026-07-20-localdb-adoption-phase2.md.tasks.json

@@ -64,12 +64,13 @@
     {
       "id": 7,
       "subject": "Task 7: DoD sweep (offline) \u2014 STOP and report after this",
-      "status": "pending",
+      "status": "completed",
       "blockedBy": [
         4,
         5,
         6
-      ]
+      ],
+      "note": "Build: 0 errors solution-wide; 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). GREPS FOUND REAL DRIFT Task 6 missed: 8 live sites still named the deleted SqliteStoreAndForwardSink - CLAUDE.md, the AdminUI /alarms/historian panel text (user-visible), HistorianAdapterActor (a <see cref> that did NOT warn), Runtime + Host + 2 Driver.Historian.Gateway doc comments, 1 gateway test comment, docs/drivers/Historian.Wonderware.md; plus docs/AlarmTracking.md still claimed a Validate() startup warning for a relative DatabasePath (that branch is gone). All fixed. Code refs to AlarmHistorian:DatabasePath now reduce to exactly two intentional ones: AlarmSfLegacyMigrator.LegacyPathKey and its test. No 'new SqliteConnection' in Core.AlarmHistorian. Both exact-set pins assert the 3-table set, both directions. Guard-deletion evidence (both vacuous passes + the pin inventory) consolidated into the recon doc."
     },
     {
       "id": 8,