feat(import): add the import page, multi-select add and the favorite platform

src/utils/manualGames.js

@@ -7,6 +7,12 @@ const JSON_HEADERS = {'Content-Type': 'application/json'};
 // positive keys; Auth also takes only those as background or banner.
 export const isSteamKey = (appid) => Number(appid) > 0;
 
+// Core's limit of a game's platform (ManualGameUpdate.MAX_PLATFORM_LENGTH).
+export const MAX_PLATFORM_LENGTH = 32;
+
+// Two decimals: then hoursToMinutes gives back the same minute.
+export const toHours = (minutes) => (minutes > 0 ? String(Math.round((minutes / 60) * 100) / 100) : '');
+
 export const hoursToMinutes = (hours) => {
     const value = Number(String(hours).replace(',', '.'));
     return Number.isFinite(value) && value > 0 ? Math.round(value * 60) : 0;