feat(17-04): menu:import-winter with the D-05 type map and read-only export SQL

- link to url, blog_categories to all-journal-categories, --map old=new on top; page entries dropped
- entries of unknown types or stale registry references dropped with their subtree, one report line per dropped or remapped entry
- ids, menu_id, parent_id, nest columns and sort_order kept; setval for both tables; --force, --dry-run, empty files copy nothing
- scripts/winter-export-menus.sql and winter-export-entries.sql
- TestMenuImportSmoke

scripts/winter-export-entries.sql

@@ -0,0 +1,38 @@
+-- Menu entries of a WinterCMS site with the Golem15.Menu plugin, one JSON
+-- object per line: the --entries input of menu:import-winter.
+--
+--   mysql -N -B --raw <database> < winter-export-entries.sql > menu-entries.jsonl
+--
+-- Read-only: it selects from the menu entries table and changes nothing.
+-- JSON_OBJECT needs MySQL 5.7.8+ or MariaDB 10.2.3+.
+--
+-- Check the table name on the server before running:
+--   SHOW TABLES LIKE '%menu_menu_entries';
+-- This file assumes golem15_menu_menu_entries.
+--
+-- Check the entry types first; the command maps link to url and
+-- blog_categories to all-journal-categories, drops page entries, and drops
+-- any other type unless --map old=new names its new type:
+--   SELECT type, COUNT(*) FROM golem15_menu_menu_entries GROUP BY type;
+SELECT JSON_OBJECT(
+    'id', e.id,
+    'menu_id', e.menu_id,
+    'parent_id', e.parent_id,
+    'nest_left', e.nest_left,
+    'nest_right', e.nest_right,
+    'nest_depth', e.nest_depth,
+    'sort_order', e.sort_order,
+    'type', e.type,
+    'title', e.title,
+    'url', e.url,
+    'reference', e.reference,
+    'code', e.code,
+    'icon', e.icon,
+    'css_class', e.css_class,
+    'target', e.target,
+    'is_published', e.is_published,
+    'created_at', e.created_at,
+    'updated_at', e.updated_at
+)
+FROM golem15_menu_menu_entries e
+ORDER BY e.id;