M2: German CSV importer + reconciliation of all 4 fixtures

- German-dialect scalar parsers in Core (GermanNumber/Money/Date, ValueCell):
  decimal comma, thousands dot, unit suffixes, € currency, both date shapes.
- Declarative MappingProfile + RowClassifier (skip summary/blank/all-zero rows) +
  CsvImporter (CsvHelper) staging readings/events/manual-costs, with auto swap
  detection on register decreases and month-end anchoring for interleaved oil dates.
- Four built-in ReferenceProfiles (Strom/Wasser/Heizöl/Kosten).
- ImportService: commit as revertible import_batch + wholesale consumption recompute
  per affected meter (NormalizationService/MeterConfigFactory), revert by batch.
- Reconciliation tests: all 4 CSVs match the sheet's own columns within tolerance
  (electricity 5 meters + Netz Einsparung, water swap→12, oil tank incl. deliveries +
  burner hours, cost category totals). Commit/revert round-trip verified on Timescale.

69 tests green (53 Core + 16 integration).

Known follow-up (polish): historical imports can contend with the 30-day compression
policy's background job; tests pause it. Consider retry-on-deadlock or deferred
compression for large historical imports in production.

Claude-Session: https://claude.ai/code/session_01WujdMtMJPbxDpDnMeK22rr

tests/Integration.Tests/MeterVault.Integration.Tests.csproj

@@ -14,6 +14,11 @@
     <Using Include="Xunit" />
   </ItemGroup>
 
+  <!-- The four reference CSVs are golden fixtures; link (don't copy) from sampledata/. -->
+  <ItemGroup>
+    <Content Include="..\..\sampledata\*.csv" Link="fixtures\%(Filename)%(Extension)" CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\..\src\App\MeterVault.App.csproj" />
   </ItemGroup>