feat: per-user feedback AI prompt template with placeholder keys

db/migration.sql

@@ -670,3 +670,11 @@ INSERT INTO settings (key, value) VALUES ('feedback_ai_prompt','Ты — пом
 
 ФОРМАТ ОТВЕТА: только текст отзыва, без лишних элементов.') ON CONFLICT (key) DO NOTHING;
 INSERT INTO settings (key, value) VALUES ('notify_feedback_ai_ready','false') ON CONFLICT (key) DO NOTHING;
+
+CREATE TABLE IF NOT EXISTS user_settings (
+  user_id INT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+  key TEXT NOT NULL,
+  value TEXT,
+  updated_at TIMESTAMPTZ DEFAULT now(),
+  PRIMARY KEY (user_id, key)
+);