fix: use dollar-quoting for PL/pgSQL trigger function

The previous single-quote syntax with escaped quotes was split by
split_sql_statements on semicolons inside the function body.
Use $$ quoting to avoid quote escaping issues.

libs/migrate/sql/m20250628_000080_add_message_reactions_and_search.sql

@@ -29,12 +29,12 @@ CREATE INDEX IF NOT EXISTS idx_room_message_content_tsv ON room_message USING GI
 
 -- Trigger to auto-update content_tsv on insert/update
 CREATE OR REPLACE FUNCTION room_message_tsv_trigger() RETURNS TRIGGER AS
-'
-    BEGIN
-        NEW.content_tsv := to_tsvector(''simple'', COALESCE(NEW.content, ''''));
-        RETURN NEW;
-    END;
-' LANGUAGE plpgsql;
+$$
+BEGIN
+    NEW.content_tsv := to_tsvector('simple', COALESCE(NEW.content, ''));
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
 
 CREATE TRIGGER room_message_tsv_update
     BEFORE INSERT OR UPDATE