Add tests and edit comments if the item they're replying to has been edited

sql/queries.sql

@@ -1,5 +1,8 @@
-/* name: ItemExists :one */
-SELECT COUNT(1) FROM replied_items WHERE item_type = ? AND id = ? AND updated_time = ?;
+/* name: GetItem :one */
+SELECT * FROM replied_items WHERE item_type = ? AND id = ? LIMIT 1;
 
 /* name: AddItem :exec */
-INSERT OR REPLACE INTO replied_items (id, item_type, updated_time) VALUES (?, ?, ?);
+INSERT OR REPLACE INTO replied_items (id, reply_id, item_type, updated_time) VALUES (?, -1, ?, ?);
+
+/* name: SetReplyID :exec */
+UPDATE replied_items SET reply_id = ? WHERE id = ?;

sql/schema.sql

@@ -1,5 +1,6 @@
 CREATE TABLE IF NOT EXISTS replied_items (
   id           INT  NOT NULL PRIMARY KEY,
+  reply_id     INT  NOT NULL,
   item_type    TEXT NOT NULL CHECK( item_type IN ('p', 'c') ),
   updated_time INT  NOT NULL,
   UNIQUE(id, item_type)