feat(uat-batch-11): picker polish + BulkAddBerthsWizard currency + DocumentsHub root cleanup

- BulkAddBerthsWizard `priceCurrency` row + apply-to-all swapped from
  freetext Input to the shared CurrencySelect. Same idiom as
  berth-form + expense-form-dialog.
- /api/v1/yachts/autocomplete no longer short-circuits to `[]` when
  the search query is empty — the service returns the top 20
  most-recently-updated yachts so the picker has a useful default
  view the moment it opens. Saves the rep from a dead-end empty
  state.
- YachtPicker gains a fallback useQuery against `/api/v1/yachts/{id}`
  when the selected yacht isn't present in the current autocomplete
  window. Trigger label now shows the real name (was falling back to
  "Yacht <uuid-prefix>" when a parent pre-selected a value from a URL
  param).
- DocumentsHub: breadcrumb row only renders when a folder is
  selected. The "Home / All documents" placeholder was wasted
  vertical space above the PageHeader on the root view.

tsc clean. 1419/1419 vitest pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/api/v1/yachts/autocomplete/handlers.ts

@@ -6,10 +6,7 @@ import { autocomplete } from '@/lib/services/yachts.service';
 
 export const autocompleteHandler: RouteHandler = async (req, ctx) => {
   try {
-    const q = req.nextUrl.searchParams.get('q');
-    if (!q) {
-      return NextResponse.json({ data: [] });
-    }
+    const q = req.nextUrl.searchParams.get('q') ?? '';
     const yachts = await autocomplete(ctx.portId, q);
     return NextResponse.json({ data: yachts });
   } catch (error) {