Move document search_vector from documents to document_versions

Now that title lives on document_versions, the full-text search vector
belongs there too. Drop the generated column and GIN index from
documents, recreate them on document_versions, and update the document
filter to query the latest version's search_vector.

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/coredata/migrations/20260407T120000Z.sql

@@ -16,3 +16,14 @@
 ALTER TABLE documents ALTER COLUMN title DROP NOT NULL;
 
 ALTER TABLE documents DROP COLUMN description;
+
+-- Move search_vector from documents to document_versions.
+DROP INDEX documents_search_idx;
+ALTER TABLE documents DROP COLUMN search_vector;
+
+ALTER TABLE document_versions ADD COLUMN search_vector tsvector
+GENERATED ALWAYS AS (
+    to_tsvector('simple', COALESCE(title, ''))
+) STORED;
+
+CREATE INDEX document_versions_search_idx ON document_versions USING gin(search_vector);