SDD §8 panels (PV/oil/meter-detail) + fix reference-data-in-Docker

Complete the SDD §8 dashboard views that were deferred at the M5 boundary,
and fix a shipping bug that left the Docker demo empty.

Bug: "Load reference data" created meters/tank/tariffs but imported zero
readings in Docker. Root cause: sampledata/ was excluded by .dockerignore and
never copied into the build stage, so the App csproj's linked Content glob
resolved to nothing at publish time; ReferenceDataImporter then silently
skipped the missing CSVs after already writing its marker meter, leaving the
DB permanently "loaded" but empty.
  - .dockerignore: stop excluding sampledata/
  - Dockerfile: COPY sampledata/ into the build stage
  - ReferenceDataImporter: fail-fast (validate CSVs exist before the marker
    meter) and throw instead of silently skipping a missing file
  - Program.cs + MeterVaultOptions: opt-in MeterVault__SeedReferenceData
    (compose METERVAULT_SEED=true) for a one-command populated demo

New SDD §8 panels (read models in Infrastructure/Dashboard, Blazor pages):
  - §8.4 Solar/PV (/solar): generation from GenerationCounter meters;
    self-consumption / autarky % / self-consumption % / savings derived from
    meters tagged total_load & grid_import via Meter.Meta role config
    (MeterRoles/MeterMeta) — nothing hardcoded by name.
  - §8.5 Oil/consumable (/consumables): tank level (cm→L calibrated), fill
    gauge, deliveries log, burner runtime, effective L/h (fixed/empirical),
    forecast-to-empty, tariff cost, monthly series.
  - §8.6 Meter detail (/meters/{id}): raw readings, normalized consumption,
    source status, tariff timeline, events, measured-vs-estimated markers.
  - Reusable SeriesChart component; nav links; Meters list rows link to detail.

Tests: MeterMetaTests (Core, +10); DashboardRenderTests extended to assert the
three panel services compute real figures and the new routes render (108 total,
all green). Live-verified in Docker: seed imports 302 readings / 347 consumption
rows; panels render (generation 16,481 kWh, oil 3,967 L) cross-checking the DB.

Claude-Session: https://claude.ai/code/session_01Lz2RqAsnQhetqWNoCDfexK

src/Infrastructure/Import/ReferenceDataImporter.cs

@@ -33,6 +33,10 @@ public sealed class ReferenceDataImporter(MeterVaultDbContext db, ImportService
             return;
         }
 
+        // Fail fast BEFORE creating the marker meter: if the CSVs are missing (e.g. not shipped in
+        // the image) we must not seed a half-loaded dataset that IsLoadedAsync then reports as done.
+        EnsureSampleFilesPresent(sampleDataDirectory);
+
         await DatabaseSeeder.SeedAsync(_db, cancellationToken).ConfigureAwait(false);
 
         var electricity = await EnergyTypeIdAsync("electricity", cancellationToken).ConfigureAwait(false);
@@ -48,6 +52,11 @@ public sealed class ReferenceDataImporter(MeterVaultDbContext db, ImportService
         var oilTank = Meter("Öltank", oil, MeterMode.ConsumableBalance, "L");
         var burner = Meter("Brenner", oil, MeterMode.RuntimeCounter, "h");
 
+        // Tag the PV meters' roles (config, not hardcoded names) so the Solar panel can derive
+        // self-consumption = total_load − grid_import and savings generically (SDD §8.4).
+        haus.Meta = MeterMeta.WithRole(haus.Meta, MeterRoles.TotalLoad);
+        netz.Meta = MeterMeta.WithRole(netz.Meta, MeterRoles.GridImport);
+
         _db.Meters.AddRange(haus, netz, auto, solar1, solar2, wasser, oilTank, burner);
         await _db.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
 
@@ -86,12 +95,32 @@ public sealed class ReferenceDataImporter(MeterVaultDbContext db, ImportService
         Columns = [new ColumnMapping { Index = 3, Role = MappingRole.ManualCost, CategoryId = heizungCategoryId }],
     };
 
+    private static readonly string[] RequiredFiles = [ElectricityFile, WaterFile, OilFile, CostsFile];
+
+    /// <summary>Throws a clear error if the sample directory or any reference CSV is missing, so a
+    /// failed load surfaces to the user instead of silently seeding meters with no data.</summary>
+    private static void EnsureSampleFilesPresent(string sampleDataDirectory)
+    {
+        if (!Directory.Exists(sampleDataDirectory))
+        {
+            throw new DirectoryNotFoundException(
+                $"Reference-data directory not found: '{sampleDataDirectory}'. The bundled Energiebilanz CSVs are missing from this deployment.");
+        }
+
+        var missing = RequiredFiles.Where(f => !File.Exists(Path.Combine(sampleDataDirectory, f))).ToList();
+        if (missing.Count > 0)
+        {
+            throw new FileNotFoundException(
+                $"Reference CSV(s) missing from '{sampleDataDirectory}': {string.Join(", ", missing)}.");
+        }
+    }
+
     private async Task ImportSheetAsync(string dir, string file, MappingProfile profile, CancellationToken cancellationToken)
     {
         var path = Path.Combine(dir, file);
         if (!File.Exists(path))
         {
-            return;
+            throw new FileNotFoundException($"Reference CSV disappeared during import: '{path}'.", path);
         }
 
         StagedImport staged;