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/app/globals.css

@@ -197,6 +197,15 @@
   --header-clearance: 4.5rem;
   /* StickySubmit with its 48px button (~4.6rem) plus breathing room. */
   --sticky-submit-clearance: 5.5rem;
+  /*
+    Toasts sit above the sticky save bar. Below sm also above the bottom nav,
+    which carries the quick-add button (nav + 1rem + 3rem, less than the bar).
+  */
+  --toast-offset-bottom: calc(var(--bottom-nav-height) + var(--sticky-submit-clearance) + 0.5rem);
+
+  @variant sm {
+    --toast-offset-bottom: calc(var(--safe-area-bottom) + var(--sticky-submit-clearance) + 0.5rem);
+  }
 }
 
 @layer base {