[AZ-484] Fix multi-source tile reads: drop Dapper enum handler

Two integration-test failures uncovered after the initial commit:

1) GetTilesByRegionAsync outer ORDER BY referenced 'updated_at' but
   the inner DISTINCT ON subquery aliased it to 'UpdatedAt' (Postgres
   folds to 'updatedat'). DISTINCT ON already guarantees one row per
   (latitude, longitude, ...) so the third tiebreak was unreachable;
   removed it.

2) Dapper 2.1.35 silently bypasses SqlMapper.TypeHandler<T> for enum
   types during read deserialization (Dapper issue #259). The
   TileSourceTypeHandler worked for writes but reads fell through to
   Enum.TryParse, which cannot map 'google_maps' to GoogleMaps.

   Pivoted: TileEntity.Source is now a string (the wire value).
   TileSource enum stays as the public producer surface in
   Common.Enums; TileSourceConverter (Common.Enums) provides
   ToWireValue / FromWireValue / IsValidWireValue at the boundary.
   TileSourceTypeHandler deleted; registration removed from
   DapperEnumTypeHandlers.RegisterAll.

   tile-storage.md Inv-5 amended to document the storage choice.
   _docs/LESSONS.md L-001 records the Dapper bypass for future cycles.

Full suite passes (213 unit + integration suite incl. AZ-484
AC-1..AC-5, security SEC-01..SEC-04, AZ-356/362/357).

Co-authored-by: Cursor <cursoragent@cursor.com>

SatelliteProvider.Tests/EnumStringTypeHandlerTests.cs

@@ -137,107 +137,4 @@ public class EnumStringTypeHandlerTests
         DapperEnumTypeHandlers.RegisterAll();
         DapperEnumTypeHandlers.RegisterAll();
     }
-
-    [Theory]
-    [InlineData(TileSource.GoogleMaps, "google_maps")]
-    [InlineData(TileSource.Uav, "uav")]
-    public void TileSourceHandler_SetValue_WritesContractWireValue_AZ484(TileSource value, string expected)
-    {
-        // Arrange
-        var handler = new TileSourceTypeHandler();
-        var param = new NpgsqlParameter();
-
-        // Act
-        handler.SetValue(param, value);
-
-        // Assert
-        param.Value.Should().Be(expected);
-        param.DbType.Should().Be(DbType.String);
-    }
-
-    [Theory]
-    [InlineData("google_maps", TileSource.GoogleMaps)]
-    [InlineData("GOOGLE_MAPS", TileSource.GoogleMaps)]
-    [InlineData("uav", TileSource.Uav)]
-    [InlineData("UAV", TileSource.Uav)]
-    public void TileSourceHandler_Parse_AcceptsContractWireValue_AZ484(string raw, TileSource expected)
-    {
-        // Arrange
-        var handler = new TileSourceTypeHandler();
-
-        // Act
-        var result = handler.Parse(raw);
-
-        // Assert
-        result.Should().Be(expected);
-    }
-
-    [Theory]
-    [InlineData(TileSource.GoogleMaps)]
-    [InlineData(TileSource.Uav)]
-    public void TileSourceHandler_RoundTrip_PreservesValue_AZ484(TileSource value)
-    {
-        // Arrange
-        var handler = new TileSourceTypeHandler();
-        var param = new NpgsqlParameter();
-        handler.SetValue(param, value);
-
-        // Act
-        var roundTripped = handler.Parse(param.Value!);
-
-        // Assert
-        roundTripped.Should().Be(value);
-    }
-
-    [Fact]
-    public void TileSourceHandler_Parse_UnknownString_ThrowsDataException_AZ484()
-    {
-        // Arrange
-        var handler = new TileSourceTypeHandler();
-
-        // Act
-        Action act = () => handler.Parse("satar");
-
-        // Assert — Inv-1: unknown sources surface, not silently coerce (coderule.mdc: never suppress errors).
-        act.Should().Throw<DataException>().WithMessage("*satar*");
-    }
-
-    [Fact]
-    public void TileSourceHandler_Parse_NullValue_ThrowsDataException_AZ484()
-    {
-        // Arrange
-        var handler = new TileSourceTypeHandler();
-
-        // Act
-        Action act = () => handler.Parse(null!);
-
-        // Assert
-        act.Should().Throw<DataException>();
-    }
-
-    [Fact]
-    public void TileSourceHandler_Parse_DbNullValue_ThrowsDataException_AZ484()
-    {
-        // Arrange
-        var handler = new TileSourceTypeHandler();
-
-        // Act
-        Action act = () => handler.Parse(DBNull.Value);
-
-        // Assert
-        act.Should().Throw<DataException>();
-    }
-
-    [Fact]
-    public void RegisterAll_RegistersTileSourceHandler_AZ484()
-    {
-        // Arrange / Act
-        DapperEnumTypeHandlers.RegisterAll();
-
-        // Assert — registration is idempotent and the handler emits the contract wire value.
-        var probe = new TileSourceTypeHandler();
-        var param = new NpgsqlParameter();
-        probe.SetValue(param, TileSource.GoogleMaps);
-        param.Value.Should().Be("google_maps");
-    }
 }