refactor(db): split revision preview from meta_json

Preview BIRD-фрагменты в config_revision_preview; meta_json только счётчик префиксов.

Co-authored-by: Cursor <[email protected]>

migrations/sqlite/000015_revision_preview.down.sql

@@ -0,0 +1,9 @@
+UPDATE config_revision
+SET meta_json = json_set(
+    meta_json,
+    '$.preview_fragments',
+    json(COALESCE((SELECT fragments FROM config_revision_preview p WHERE p.revision_id = config_revision.id), '{}'))
+)
+WHERE id IN (SELECT revision_id FROM config_revision_preview);
+
+DROP TABLE IF EXISTS config_revision_preview;

migrations/sqlite/000015_revision_preview.up.sql

@@ -0,0 +1,13 @@
+CREATE TABLE config_revision_preview (
+    revision_id   TEXT NOT NULL PRIMARY KEY REFERENCES config_revision (id) ON DELETE CASCADE,
+    fragments     TEXT NOT NULL DEFAULT '{}'
+);
+
+INSERT INTO config_revision_preview (revision_id, fragments)
+SELECT id, json(COALESCE(json_extract(meta_json, '$.preview_fragments'), '{}'))
+FROM config_revision
+WHERE json_extract(meta_json, '$.preview_fragments') IS NOT NULL;
+
+UPDATE config_revision
+SET meta_json = json_remove(meta_json, '$.preview_fragments')
+WHERE json_extract(meta_json, '$.preview_fragments') IS NOT NULL;