fix(btw): 修复长对话上下文预算与旁路输入布局

db/schema.sql

@@ -1108,3 +1108,7 @@ CREATE TABLE IF NOT EXISTS side_question_requests (
 );
 CREATE UNIQUE INDEX IF NOT EXISTS idx_side_request_running ON side_question_requests(session_key) WHERE status='running';
 CREATE INDEX IF NOT EXISTS idx_side_requests_history ON side_question_requests(session_key,ordinal DESC);
+
+-- Additive v3 archive fields; old archives restore these as empty objects.
+ALTER TABLE side_question_sessions ADD COLUMN IF NOT EXISTS memory JSONB NOT NULL DEFAULT '{}';
+ALTER TABLE side_question_requests ADD COLUMN IF NOT EXISTS context_info JSONB NOT NULL DEFAULT '{}';