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

src/Infrastructure/Options/MeterVaultOptions.cs

@@ -0,0 +1,24 @@
+namespace MeterVault.Infrastructure.Options;
+
+/// <summary>
+/// Root application options, bound from the "MeterVault" configuration section.
+/// Secrets (broker tokens etc.) live on individual endpoints by reference, not here.
+/// </summary>
+public sealed class MeterVaultOptions
+{
+    public const string SectionName = "MeterVault";
+
+    /// <summary>IANA timezone used for local-midnight bucketing and display (SDD §10).</summary>
+    public string TimeZone { get; set; } = "Europe/Berlin";
+
+    public string Currency { get; set; } = "EUR";
+
+    /// <summary>Default UI locale: 'en' (OSS default) or 'de'.</summary>
+    public string Locale { get; set; } = "en";
+
+    /// <summary>Run EF migrations on startup. Disable for tests that migrate out-of-band.</summary>
+    public bool RunMigrationsAtStartup { get; set; } = true;
+
+    /// <summary>How long full-resolution raw readings are retained (SDD §5.5, default 3 years).</summary>
+    public int RawRetentionDays { get; set; } = 1095;
+}