fix: add missing Ernten/Schleuderungen list and detail views

The sidebar nav sent both entries straight to their "new" creation
form, with no list page to ever browse what had been created -
Schleuderung creation didn't even redirect to a detail page, just to
/colonies, so a saved extraction left no trace anywhere in the UI.

- New /harvests and /extractions list pages (mirrors the existing
  products/apiaries list pattern).
- New /extractions/[id] detail page + edit dialog, matching the
  harvests one that already existed but had nothing linking to it.
- Sidebar "Ernten"/"Schleuderungen" now point at the list pages instead
  of the creation forms.
- Extraction creation now redirects to its detail page instead of
  /colonies.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

ApiCore-Frontend/src/app/(app)/sidebar.tsx

@@ -70,8 +70,8 @@ const NAV_GROUPS: NavGroup[] = [
   {
     label: "Ernte & Lager",
     items: [
-      { label: "Ernten", href: "/harvests/new", icon: Scissors },
-      { label: "Schleuderungen", href: "/extractions/new", icon: FlaskConical },
+      { label: "Ernten", href: "/harvests", icon: Scissors },
+      { label: "Schleuderungen", href: "/extractions", icon: FlaskConical },
       { label: "Honigchargen", href: "/honey-batches", icon: Droplet },
       { label: "Abfüllungen", href: "/bottling", icon: Package },
       { label: "Produkte", href: "/products", icon: ShoppingBag },