Add has_been_merged to DB

sync-server/src/app_state/database/migrations/20251019103154_add_has_been_merged.sql

@@ -0,0 +1,13 @@
+ALTER TABLE documents ADD COLUMN has_been_merged BOOLEAN NOT NULL DEFAULT False;
+
+DROP VIEW latest_document_versions;
+
+CREATE VIEW IF NOT EXISTS latest_document_versions AS --recreate view as it now includes one more field
+SELECT d.*
+FROM documents d
+INNER JOIN (
+    SELECT MAX(vault_update_id) AS max_version_id
+    FROM documents
+    GROUP BY document_id
+) max_versions
+ON d.vault_update_id = max_versions.max_version_id;