feat: add Next Lesson widget and enhance existing widgets

- Implemented a new Next Lesson widget to display the upcoming lesson details on the home screen.
- Updated Today widget to dynamically adjust the number of lessons displayed based on available space.
- Enhanced the Settings screen to allow users to manage hidden lessons more effectively.
- Introduced harmonized color palettes for better visual consistency across themes.
- Updated the timetable API to support a new range parameter for semester-based queries.
- Added tests to ensure the new semester range functionality works as expected.
- Refactored widget styling for improved appearance on devices with different Android versions.

server/index.js

@@ -29,8 +29,8 @@ app.use("/api", (_req, res, next) => {
   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;
+// 2 — /api/timetable for the Android client; 3 — its range=semester.
+const API_VERSION = 3;
 
 // Liveness plus what the server currently reads from the university, without network calls.
 app.get("/api/health", async (_req, res) => {
@@ -110,6 +110,8 @@ app.get("/api/timetable", async (req, res, next) => {
         group,
         from,
         days: req.query.days,
+        range: req.query.range === "semester" ? "semester" : undefined,
+        today: todayIso(),
       }),
     );
   } catch (e) {