fix: T4a browser check findings

- Withdrawal wording from one backend helper everywhere ("bis
  einschließlich TT.MM. – ab TT.MM. wieder erntefähig", year when it
  crosses New Year); withdrawal-status returns lastBlockedDay and the
  ready text, the frontend no longer computes dates
- Calendar events name colony or apiary, withdrawal events carry
  product and detail; compact withdrawal rows on mobile
- One bottling warning per colony and treatment; pre-save hint
- Offline: online-only actions disabled with a reason, cached data
  shows its timestamp, open sheets block submit offline
- Mobile: no horizontal scroll at 360 px, touch targets >= 44 px,
  toasts and the add button no longer cover content
- Cleanup sheet without destructive preselection; natural sort of
  colony codes; collapsible automation rule cards; varroa list newest
  first with chart axes; text fixes

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

ApiCore-Frontend/src/lib/text/plural.spec.ts

@@ -0,0 +1,10 @@
+import { describe, expect, it } from "vitest";
+import { entryCountText } from "./plural";
+
+describe("entryCountText", () => {
+  it("uses the singular for exactly one entry", () => {
+    expect(entryCountText(0)).toBe("0 Einträge");
+    expect(entryCountText(1)).toBe("1 Eintrag");
+    expect(entryCountText(2)).toBe("2 Einträge");
+  });
+});

ApiCore-Frontend/src/lib/text/plural.ts

@@ -0,0 +1,4 @@
+/** "1 Eintrag", "0 Einträge", "2 Einträge". */
+export function entryCountText(count: number): string {
+  return `${count} ${count === 1 ? "Eintrag" : "Einträge"}`;
+}