feat(library): add the merge duplicate dialog

src/utils/corrections.js

@@ -33,3 +33,11 @@ export const saveCorrection = (appid, field, value) =>
  * DELETE: back to the source's value, 204.
  */
 export const resetCorrection = (appid, field) => apiFetch(url(appid, field), {method: 'DELETE'});
+
+/**
+ * POST: 200 {appid} = the key the game lives under now; 400 {code: SAME_GAME | STEAM_GAMES}, 403 below AUDITOR,
+ * 404 {code: GAME_NOT_FOUND} for a game not in ToBePlayed.
+ */
+export const mergeGame = (appid, otherAppid) =>
+    apiFetch(`${import.meta.env.VITE_CORE_API_URL}/api/library/games/${appid}/merge`,
+        {method: 'POST', headers: JSON_HEADERS, body: JSON.stringify({otherAppid})});