Flow: count generation meters as sources (grid + solar → house)

A meter's flow value is now its throughput — consumption OR generation output —
so a generation meter (solar) acts as a source that can feed downstream meters.
Setting a load meter's upstream to {grid, solar} now splits its consumption
across both proportionally, and the remainder under the sources (grid + solar −
load) surfaces as "Other" = export + battery/inverter losses. Negative values
(savings/balance virtuals) are clamped to 0 (a ribbon can't be negative). The
per-type KPI is relabelled "Top-level throughput" since it now spans generation.

Test: Generation_meter_counts_as_source (grid 75 + solar-gen 30 → house 40 →
28.57/11.43 split, 65 remainder). 69 Core + 48 Integration = 117 green.
Live-verified: electricity flow now shows Solar 1/2 as source nodes.

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

src/Infrastructure/Dashboard/FlowService.cs

@@ -33,12 +33,16 @@ public sealed class FlowService(IDbContextFactory<MeterVaultDbContext> contextFa
         var fromUtc = ToUtc(from);
         var toUtc = ToUtc(to);
 
+        // A meter's flow value is its throughput: consumption OR generation output — so a generation
+        // meter (solar) can act as a source feeding downstream meters (grid + solar → house). A meter
+        // is normally one kind, so summing both kinds is that meter's flow. Negatives (savings/balance
+        // virtual meters) are clamped to 0 — a flow ribbon can't be negative.
         var sums = await db.Consumption.AsNoTracking()
-            .Where(c => c.Time >= fromUtc && c.Time < toUtc && c.Kind == ConsumptionKind.Consumption)
+            .Where(c => c.Time >= fromUtc && c.Time < toUtc)
             .GroupBy(c => c.MeterId)
             .Select(g => new { MeterId = g.Key, Total = g.Sum(x => x.Amount) })
             .ToListAsync(cancellationToken).ConfigureAwait(false);
-        var value = sums.Where(s => meterIds.Contains(s.MeterId)).ToDictionary(s => s.MeterId, s => s.Total);
+        var value = sums.Where(s => meterIds.Contains(s.MeterId)).ToDictionary(s => s.MeterId, s => Math.Max(0, s.Total));
         double V(int id) => value.GetValueOrDefault(id);
 
         var links = await db.MeterLinks.AsNoTracking()