feat(localdb): rewire SiteEventLogger onto the consolidated site database

Completes Task 5a of the LocalDb Phase 1 adoption plan. The GUID-id half landed
with Task 2 (727fa48c) because leaving it out would have committed a writer that
could not satisfy site_events.id NOT NULL; this is the connection half, which
was blocked on Task 3.

SiteEventLogger owned a SqliteConnection built from SiteEventLogOptions
.DatabasePath. It now takes ILocalDb and gets that connection from
CreateConnection() - already open, pragma-configured, and carrying the
zb_hlc_next() UDF that site_events' capture triggers call. It still owns and
disposes the connection; WithConnection's signature and locking semantics are
untouched, so EventLogQueryService and EventLogPurgeService are unaffected.

The connectionStringOverride seam is deleted rather than preserved. site_events
is a replicated table, so a raw connection lacks the UDF and fails closed on
every insert - an override could only produce a logger that cannot write. It had
no callers outside this class (the connectionStringOverride hits elsewhere in the
tree belong to SqliteAuditWriter, a different type).

Tests: a shared TestLocalDb helper gives each fixture a real ILocalDb over a temp
file. Real rather than stubbed on purpose - a stub handing back a bare
SqliteConnection would pass today and fail closed the moment the table is
registered, which is exactly the silent-wiring failure mode this family has hit
three times. ServiceWiringTests' DI path also needed AddZbLocalDb, mirroring
SiteServiceRegistration.

Verified: build 0 warnings; SiteEventLogging 70/70, Host 294/294,
SiteRuntime 530/530.

Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts

tests/ZB.MOM.WW.ScadaBridge.SiteEventLogging.Tests/SchemaIndexTests.cs

@@ -13,12 +13,14 @@ public class SchemaIndexTests : IDisposable
     private readonly SiteEventLogger _logger;
     private readonly SqliteConnection _verifyConnection;
     private readonly string _dbPath;
+    private readonly TestLocalDb _localDb;
 
     public SchemaIndexTests()
     {
         _dbPath = Path.Combine(Path.GetTempPath(), $"test_index_{Guid.NewGuid()}.db");
         var options = Options.Create(new SiteEventLogOptions { DatabasePath = _dbPath });
-        _logger = new SiteEventLogger(options, NullLogger<SiteEventLogger>.Instance);
+        _localDb = TestLocalDb.Create(_dbPath);
+        _logger = new SiteEventLogger(options, NullLogger<SiteEventLogger>.Instance, _localDb.Db);
 
         _verifyConnection = new SqliteConnection($"Data Source={_dbPath}");
         _verifyConnection.Open();
@@ -28,7 +30,8 @@ public class SchemaIndexTests : IDisposable
     {
         _verifyConnection.Dispose();
         _logger.Dispose();
-        if (File.Exists(_dbPath)) File.Delete(_dbPath);
+        _localDb.Dispose();
+        TestLocalDb.DeleteFiles(_dbPath);
     }
 
     [Fact]