M3: live ingestion (MQTT/Tasmota + Home Assistant)

- PayloadExtractor: dot-path value/time extraction (Tasmota ENERGY.Total, bare scalars).
- MqttTopicMatcher: standard +/# wildcard matching.
- IngestionService: scale/offset, idempotent upsert on (meter_id, time), and a spurious-
  decrease guard for monotonic registers (allowed only with a reset/swap event) + source
  last-seen status.
- MqttMessageRouter + MqttIngestionWorker (MQTTnet 5): per-endpoint persistent connections,
  topic subscription, graceful degradation; secrets resolved by env-var reference.
- Home Assistant: HaStateClient (REST /api/states parse) + HomeAssistantWorker polling on
  each source's interval. HA-via-MQTT also works through the MQTT path.
- Ingestion workers gated by MeterVault:EnableLiveIngestion (off in tests).

85 tests green (53 Core + 32 integration): Tasmota payload → reading verified end to end.

Follow-up (polish): HA WebSocket push (state_changed) as an alternative to REST poll;
source-topic index caching in the router.

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

src/Infrastructure/DependencyInjection.cs

@@ -1,5 +1,6 @@
 using MeterVault.Core.Normalization;
 using MeterVault.Infrastructure.Import;
+using MeterVault.Infrastructure.Ingestion;
 using MeterVault.Infrastructure.Normalization;
 using MeterVault.Infrastructure.Persistence;
 using Microsoft.EntityFrameworkCore;
@@ -24,7 +25,21 @@ public static class DependencyInjection
         services.AddScoped<NormalizationService>();
         services.AddScoped<CsvImporter>();
         services.AddScoped<ImportService>();
+        services.AddScoped<IngestionService>();
+        services.AddScoped<MqttMessageRouter>();
 
         return services;
     }
+
+    /// <summary>
+    /// Registers the live-ingestion background workers (MQTT/Tasmota + Home Assistant). Kept
+    /// separate from <see cref="AddMeterVaultInfrastructure"/> so tests can opt out of brokers.
+    /// </summary>
+    public static IServiceCollection AddMeterVaultIngestion(this IServiceCollection services)
+    {
+        services.AddHttpClient();
+        services.AddHostedService<MqttIngestionWorker>();
+        services.AddHostedService<HomeAssistantWorker>();
+        return services;
+    }
 }