Feature: extended filter rules — attachment field + multi-value conditions

Adds an "Attachment" condition field (is present / of type <ext>) backed by
the RFC 5703 Sieve mime extension, matching the filename in both
Content-Disposition and Content-Type headers so real-world senders that only
put the name in Content-Type (Microsoft SMTPSVC, etc.) are caught. Users type
extensions (pdf, doc) not MIME types.

Also makes each text condition accept comma-separated multiple values emitted
as a Sieve string list (OR within the condition), so "(domain1 OR domain2)
AND attachment pdf/xml" is expressible in one rule. value is now string |
string[] (single-value rules stay strings -> backward compatible). New filter
locale keys in all 17 locales.

locales/ru/common.json

@@ -1632,7 +1632,10 @@
       "actions": "Действия",
       "add_action": "Добавить действие",
       "stop_processing": "Прекратить обработку последующих правил",
+      "attachment_type_placeholder": "напр. pdf, doc, jpg",
+      "value_placeholder_multi": "Значение (несколько через запятую)",
       "condition_fields": {
+        "attachment": "Вложение",
         "from": "От",
         "to": "Кому",
         "cc": "Копия",
@@ -1642,6 +1645,8 @@
         "body": "Тело"
       },
       "comparators": {
+        "has_any": "присутствует",
+        "has_type": "типа",
         "contains": "содержит",
         "not_contains": "не содержит",
         "is": "точно совпадает",