M4: aggregation + tariff-aware cost engine

- ContinuousAggregates migration: consumption_daily/monthly/yearly in Europe/Berlin
  buckets via migrationBuilder.Sql(..., suppressTransaction: true), with refresh policies
  (end_offset >= 1 bucket; current bucket covered by real-time aggregation).
- TariffResolver (Core): time-ranged price resolution, scope precedence meter > type > global.
- CostService: Dapper-aggregated monthly consumption × resolved unit price (+base, -feed-in),
  month-dominant pricing; category rollups over member meters + meterless manual costs.
- Tests: water cost reconciles to the sheet's Kosten column, Wasser category rollup (Dez=70€),
  monthly CAgg refresh matches base, TariffResolver unit tests.

91 tests green (56 Core + 35 integration).

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

src/Infrastructure/DependencyInjection.cs

@@ -27,6 +27,7 @@ public static class DependencyInjection
         services.AddScoped<ImportService>();
         services.AddScoped<IngestionService>();
         services.AddScoped<MqttMessageRouter>();
+        services.AddScoped<Costing.CostService>();
 
         return services;
     }