M0: scaffold solution, EF+Timescale schema, /healthz

Five-project Clean Architecture solution (Core/Infrastructure/App + Core.Tests/
Integration.Tests) on .NET 10 with central package management, snake_case EF mapping,
and shared build/style config.

- Full domain entity set + EF DbContext for the SDD §5.3 schema (singular table names).
- InitialSchema migration (relational) + TimescaleHypertables migration (raw SQL:
  create_hypertable + compression on reading, hypertable on consumption).
- App wiring: Serilog (actually wired, unlike MQTTower), DbContext, migrate-on-startup,
  /healthz. Serves plain HTTP behind a reverse proxy (no HTTPS redirect).
- deploy/Dockerfile (2-stage, ICU-capable) + docker-compose (app + timescaledb).
- Integration.Tests: shared TimescaleFixture (Testcontainers) — migrations, hypertables,
  compression policy, and /healthz all verified green (4/4).

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

deploy/docker-compose.yml

@@ -0,0 +1,47 @@
+# MeterVault self-host stack: the Blazor app + TimescaleDB.
+#   docker compose -f deploy/docker-compose.yml up -d
+# Secrets are supplied via environment variables (Section__Key double-underscore mapping)
+# with ${VAR:-default} fallbacks — never baked into the image.
+
+services:
+  db:
+    image: timescale/timescaledb:2.17.2-pg16
+    environment:
+      POSTGRES_DB: metervault
+      POSTGRES_USER: metervault
+      POSTGRES_PASSWORD: ${METERVAULT_DB_PASSWORD:-metervault}
+    volumes:
+      - metervault_db:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U metervault -d metervault"]
+      interval: 10s
+      timeout: 5s
+      retries: 10
+    restart: unless-stopped
+
+  app:
+    build:
+      context: ..
+      dockerfile: deploy/Dockerfile
+    image: ${METERVAULT_IMAGE:-metervault/metervault:local}
+    depends_on:
+      db:
+        condition: service_healthy
+    environment:
+      ConnectionStrings__Default: "Host=db;Port=5432;Database=metervault;Username=metervault;Password=${METERVAULT_DB_PASSWORD:-metervault}"
+      ASPNETCORE_ENVIRONMENT: Production
+      MeterVault__TimeZone: ${METERVAULT_TIMEZONE:-Europe/Berlin}
+      MeterVault__Currency: ${METERVAULT_CURRENCY:-EUR}
+      MeterVault__Locale: ${METERVAULT_LOCALE:-en}
+    ports:
+      - "${METERVAULT_PORT:-8080}:8080"
+    healthcheck:
+      test: ["CMD-SHELL", "curl -fsS http://localhost:8080/healthz || exit 1"]
+      interval: 15s
+      timeout: 5s
+      retries: 5
+      start_period: 30s
+    restart: unless-stopped
+
+volumes:
+  metervault_db: