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/components/documents/documents-hub.tsx

@@ -193,9 +193,9 @@ export function DocumentsHub({ portSlug }: DocumentsHubProps) {
 
   const contentPane = (
     <div className="flex-1 min-w-0 p-4 space-y-4">
-      <div className="flex items-center justify-between gap-3">
-        <FolderBreadcrumb selectedFolderId={selectedFolderId} onSelect={handleFolderSelect} />
-        {selectedFolderId !== undefined && (
+      {selectedFolderId !== undefined && (
+        <div className="flex items-center justify-between gap-3">
+          <FolderBreadcrumb selectedFolderId={selectedFolderId} onSelect={handleFolderSelect} />
           <NewDocumentMenu
             portSlug={portSlug}
             folderId={selectedFolderId}
@@ -205,8 +205,8 @@ export function DocumentsHub({ portSlug }: DocumentsHubProps) {
             entityId={isEntityFolder ? (selectedFolder!.entityId ?? undefined) : undefined}
             size="sm"
           />
-        )}
-      </div>
+        </div>
+      )}
 
       {selectedFolderId === undefined ? (
         <>