feat: add index type, included columns, filter, and comment support

- Add filter, index_type, included_columns, and comment fields to IndexInfo
- PostgreSQL: query pg_am for index type, use indnkeyatts to split key/included columns, retrieve index comments via obj_description()
- SQL Server: add type_desc, filter_definition, included columns via is_included_column
- MySQL: add INDEX_TYPE from information_schema.STATISTICS
- Oracle: add INDEX_TYPE from ALL_INDEXES
- DDL generation: add USING (PostgreSQL), type prefix + INCLUDE + WHERE (SQL Server), COMMENT ON INDEX (PostgreSQL)
- Frontend: update types, state mapping, SQL generation, and i18n translations

src/i18n/locales/en.ts

@@ -335,7 +335,12 @@ export default {
     actions: "Actions",
     indexName: "Index",
     indexColumns: "Columns",
+    indexColumnsPlaceholder: "Select columns...",
     unique: "Unique",
+    indexType: "Type",
+    includedColumns: "Included",
+    includedColumnsPlaceholder: "Select columns...",
+    filter: "Filter",
     primary: "Primary",
     drop: "Drop",
     restore: "Restore",

src/i18n/locales/zh-CN.ts

@@ -335,7 +335,12 @@ export default {
     actions: "操作",
     indexName: "索引名",
     indexColumns: "字段列表",
+    indexColumnsPlaceholder: "选择列...",
     unique: "唯一",
+    indexType: "类型",
+    includedColumns: "包含列",
+    includedColumnsPlaceholder: "选择列...",
+    filter: "过滤条件",
     primary: "主键",
     drop: "删除",
     restore: "恢复",