feat: Add Settings and Subjects screens with theme reveal functionality

- Implemented SettingsScreen for user preferences including theme selection, reminders, and notifications.
- Created SubjectsScreen to display subjects with upcoming lessons and associated details.
- Introduced ThemeReveal for a smooth transition between light and dark themes.
- Added support for managing notes and tasks related to subjects.
- Enhanced UI components for better user experience and accessibility.

server/diagnostics.js

@@ -5,7 +5,8 @@ import { roomMoves } from "./rooms.js";
 // whole text as the subject. These checks find such cells after parsing, so a new format or a
 // typo in Word shows up as soon as the document is published instead of when a student notices.
 
-const MONTHS = /(?<![а-яё])(?:январ|феврал|март|апрел|ма[йя]|июн|июл|август|сентябр|октябр|ноябр|декабр)[а-яё]*/iu;
+// "мая" is a month, "Майнор" is not.
+const MONTHS = /(?<![а-яё])(?:(?:январ|феврал|март|апрел|июн|июл|август|сентябр|октябр|ноябр|декабр)[а-яё]*|ма[йя](?![а-яё]))/iu;
 // The longest semester has about twenty weeks; "27н." is a typo, not a week.
 const LAST_WEEK = 24;