feat: add address book directories with drag-and-drop and editor picker

- Show address books in sidebar organized by personal directories and
  shared accounts, replacing the flat shared accounts list
- Make contact list items draggable with multi-select support using
  native HTML5 drag-and-drop (application/x-contact-ids MIME type)
- Add drop targets on sidebar address book items with visual feedback
- Add moveContactToAddressBook store method supporting same-account
  updates and cross-account create+delete moves
- Add address book picker dropdown in contact create/edit form
- Update ContactCategory type from sharedAccountId to addressBookId
- Add address_books translations to all 8 locales
- Fix contact-list-item tests for new selectedContactIds prop

components/contacts/contact-list-item.tsx

@@ -1,5 +1,6 @@
 "use client";
 
+import { useCallback, type DragEvent } from "react";
 import { Avatar } from "@/components/ui/avatar";
 import { cn } from "@/lib/utils";
 import type { ContactCard } from "@/lib/jmap/types";
@@ -13,19 +14,47 @@ interface ContactListItemProps {
   isChecked: boolean;
   hasSelection: boolean;
   density: Density;
+  selectedContactIds: Set<string>;
   onClick: (e: React.MouseEvent) => void;
   onCheckboxClick: (e: React.MouseEvent) => void;
 }
 
-export function ContactListItem({ contact, isSelected, isChecked, hasSelection, density, onClick, onCheckboxClick }: ContactListItemProps) {
+export function ContactListItem({ contact, isSelected, isChecked, hasSelection, density, selectedContactIds, onClick, onCheckboxClick }: ContactListItemProps) {
   const name = getContactDisplayName(contact);
   const email = getContactPrimaryEmail(contact);
   const org = contact.organizations
     ? Object.values(contact.organizations)[0]?.name
     : undefined;
 
+  const handleDragStart = useCallback((e: DragEvent<HTMLDivElement>) => {
+    // Drag all selected contacts if this one is selected, otherwise just this one
+    const ids = selectedContactIds.has(contact.id)
+      ? Array.from(selectedContactIds)
+      : [contact.id];
+
+    e.dataTransfer.effectAllowed = "move";
+    e.dataTransfer.setData("application/x-contact-ids", JSON.stringify(ids));
+    e.dataTransfer.setData("text/plain", name || email || contact.id);
+
+    // Custom drag preview
+    const preview = document.createElement("div");
+    preview.style.cssText = `
+      position: fixed; top: -9999px; left: 0;
+      padding: 8px 16px; background-color: var(--color-primary, #3b82f6);
+      color: var(--color-primary-foreground, #ffffff); border-radius: 8px;
+      box-shadow: 0 4px 12px rgba(0,0,0,0.15); font-size: 14px; font-weight: 500;
+      z-index: 9999; white-space: nowrap; pointer-events: none;
+    `;
+    preview.textContent = ids.length === 1 ? (name || "1 contact") : `${ids.length} contacts`;
+    document.body.appendChild(preview);
+    e.dataTransfer.setDragImage(preview, 0, 0);
+    requestAnimationFrame(() => preview.remove());
+  }, [contact.id, name, email, selectedContactIds]);
+
   return (
     <div
+      draggable
+      onDragStart={handleDragStart}
       onClick={onClick}
       className={cn(
         "w-full flex items-center cursor-pointer select-none transition-all duration-200 border-b border-border",