feat: add tasks and notes management for lessons

- Introduced a new feature for managing tasks and notes associated with lessons.
- Added a `NotesStore` class to handle local storage of notes in JSON format.
- Implemented UI components for displaying, adding, editing, and deleting notes.
- Enhanced the `HomeScreen`, `ScheduleScreen`, and `SubjectsScreen` to integrate notes functionality.
- Updated the API to handle versioning and added error handling for outdated endpoints.
- Improved the overall user experience with visual indicators for tasks and notes in the schedule.

server/index.js

@@ -28,11 +28,16 @@ app.use("/api", (_req, res, next) => {
   res.set("Cache-Control", "no-store");
   next();
 });
+// Raised whenever an endpoint is added or changed, so a deployment is easy to verify:
+// 2 — /api/timetable for the Android client.
+const API_VERSION = 2;
+
 // Liveness plus what the server currently reads from the university, without network calls.
 app.get("/api/health", async (_req, res) => {
   const sources = await sourceStatus().catch((e) => ({ error: e.message }));
   res.json({
     ok: true,
+    apiVersion: API_VERSION,
     parserVersion: PARSER_VERSION,
     ...sources,
     directory: indexStatus(),