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

Directory.Build.props

@@ -0,0 +1,24 @@
+<Project>
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <EnableNETAnalyzers>true</EnableNETAnalyzers>
+    <AnalysisLevel>latest</AnalysisLevel>
+    <AnalysisMode>Default</AnalysisMode>
+    <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
+    <!-- The German-dialect CSV importer parses/formats with explicit CultureInfo("de-DE");
+         invariant globalization would break it and the container needs ICU. -->
+    <InvariantGlobalization>false</InvariantGlobalization>
+  </PropertyGroup>
+
+  <!-- Test projects: mirror under tests/, name *.Tests, never packed, relaxed warnings. -->
+  <PropertyGroup Condition="$(MSBuildProjectName.EndsWith('Tests'))">
+    <IsPackable>false</IsPackable>
+    <TreatWarningsAsErrors>false</TreatWarningsAsErrors>
+  </PropertyGroup>
+
+</Project>