feat(contacts): add no-category filter, drag-drop to category, and category combo box

- Add 'No Category' sidebar item to filter uncategorized contacts
- Categories section now always visible (not just when keywords exist)
- Add drag-and-drop support on category items in sidebar to assign keywords
- Fix effectAllowed mismatch (move -> copyMove) for category drop targets
- Replace plain text categories input with combo box in contact edit form
  - Shows existing categories as clickable suggestions
  - Displays assigned categories as removable badges
  - Supports adding new categories inline
- Add translations for all 8 locales

locales/pt/common.json

@@ -1482,6 +1482,9 @@
     "title": "Contatos",
     "search_placeholder": "Pesquisar contatos...",
     "create_new": "Novo contato",
+    "no_category": "Sem categoria",
+    "category_added": "Contato adicionado a {name}",
+    "category_added_plural": "{count} contatos adicionados a {name}",
     "empty_state": "Nenhum contato",
     "empty_state_title": "Sem contatos",
     "empty_state_subtitle": "Crie seu primeiro contato ou importe de um arquivo vCard",
@@ -1625,7 +1628,8 @@
       "level_low": "Baixo",
       "categories": "Categorias",
       "categories_placeholder": "ex., Família, Amigos, Colegas",
-      "categories_hint": "Separar com vírgulas",
+      "categories_hint": "Digite para pesquisar ou adicionar",
+      "category_add": "Adicionar",
       "note": "Notas",
       "note_placeholder": "Adicionar uma nota...",
       "gender": "Gênero",