fix(statistics): feeding totals per unit instead of adding litres to kilograms

The feeding statistics summed every amount regardless of its unit, so
5 l syrup and 2 kg fondant showed as 7. The API now also returns byUnit
(units normalised: "L" = "l"), the old fields stay for compatibility,
and the statistics page shows one list per unit.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Frontend/src/app/(app)/statistics/page.tsx

@@ -293,49 +293,62 @@ function FeedingStatsPanel({ colonyLabels }: { colonyLabels: Map<string, string>
 
   return (
     <QueryState query={query} what="Futterdaten">
-      {(data) => (
-        <div className="flex flex-col gap-4">
-          <PanelHint>
-            Summe der eingetragenen Futtermengen in Liter bzw. kg, so wie sie bei der Fütterung
-            erfasst wurden.
-          </PanelHint>
-          <Card>
-            <CardHeader>
-              <CardTitle>Futterverbrauch pro Volk</CardTitle>
-            </CardHeader>
-            <CardContent>
-              <StatBarList
-                items={Object.entries(data.byColony)
-                  .sort(([, a], [, b]) => b - a)
-                  .slice(0, 10)
-                  .map(([colonyId, value]) => ({
-                    label: colonyLabels.get(colonyId) ?? colonyId,
-                    value,
-                    unit: FEED_UNIT,
-                  }))}
-                formatValue={kg}
-                emptyText="Noch keine Fütterungen erfasst."
-              />
-            </CardContent>
-          </Card>
-          <Card>
-            <CardHeader>
-              <CardTitle>Futterverbrauch pro Saison</CardTitle>
-            </CardHeader>
-            <CardContent>
-              <StatBarList
-                items={sortedRecordEntries(data.bySeason).map(([year, value]) => ({
-                  label: year,
-                  value,
-                  unit: FEED_UNIT,
-                }))}
-                formatValue={kg}
-                emptyText="Noch keine Fütterungen erfasst."
-              />
-            </CardContent>
-          </Card>
-        </div>
-      )}
+      {(data) => {
+        // One block per unit: litres and kilograms are never added up.
+        const units = Object.entries(
+          data.byUnit ?? { [FEED_UNIT]: { byColony: data.byColony, bySeason: data.bySeason } },
+        );
+        return (
+          <div className="flex flex-col gap-4">
+            <PanelHint>
+              Summe der eingetragenen Futtermengen, getrennt nach Einheit – so wie sie bei der
+              Fütterung erfasst wurden.
+            </PanelHint>
+            {units.length === 0 ? (
+              <p className="text-sm text-muted-foreground">Noch keine Fütterungen erfasst.</p>
+            ) : null}
+            {units.map(([unit, totals]) => (
+              <div key={unit} className="flex flex-col gap-4">
+                <Card>
+                  <CardHeader>
+                    <CardTitle>Futterverbrauch pro Volk ({unit})</CardTitle>
+                  </CardHeader>
+                  <CardContent>
+                    <StatBarList
+                      items={Object.entries(totals.byColony)
+                        .sort(([, a], [, b]) => b - a)
+                        .slice(0, 10)
+                        .map(([colonyId, value]) => ({
+                          label: colonyLabels.get(colonyId) ?? colonyId,
+                          value,
+                          unit,
+                        }))}
+                      formatValue={kg}
+                      emptyText="Noch keine Fütterungen erfasst."
+                    />
+                  </CardContent>
+                </Card>
+                <Card>
+                  <CardHeader>
+                    <CardTitle>Futterverbrauch pro Saison ({unit})</CardTitle>
+                  </CardHeader>
+                  <CardContent>
+                    <StatBarList
+                      items={sortedRecordEntries(totals.bySeason).map(([year, value]) => ({
+                        label: year,
+                        value,
+                        unit,
+                      }))}
+                      formatValue={kg}
+                      emptyText="Noch keine Fütterungen erfasst."
+                    />
+                  </CardContent>
+                </Card>
+              </div>
+            ))}
+          </div>
+        );
+      }}
     </QueryState>
   );
 }

ApiCore-Frontend/src/lib/statistics/types.ts

@@ -48,4 +48,6 @@ export interface HoneyStats {
 export interface FeedingStats {
   byColony: Record<string, number>;
   bySeason: Record<string, number>;
+  /** Totals per unit ("l", "kg", ...) - units are never added together. */
+  byUnit?: Record<string, { byColony: Record<string, number>; bySeason: Record<string, number> }>;
 }