feat: Enhance session handling in timetable and UI

- Introduced session types (exams, credits, consultations, coursework defenses) with distinct icons and colors for better visibility in the UI.
- Updated PlansScreen, ScheduleScreen, and WeekGrid to display session information appropriately.
- Modified CalendarView and PlansView to include session indicators in the calendar and plans.
- Enhanced LessonCard and CompactLesson to show session details and adjust styling based on session presence.
- Added new SessionMark component for consistent session representation across Android and iOS.
- Updated server logic to handle session entries from external documents, ensuring accurate timetable representation.
- Improved date parsing to accommodate session-related dates in various formats.
- Added tests to verify session handling and date parsing functionality.

server/index.js

@@ -16,6 +16,8 @@ import {
   freeRooms,
   examsOf,
   findGroups,
+  readyIndex,
+  sessionEntriesOf,
   directoryCalendar,
   todayIso,
 } from "./directory.js";
@@ -42,8 +44,9 @@ app.use("/api", (_req, res, next) => {
 // Raised whenever an endpoint is added or changed, so a deployment is easy to verify:
 // 2 — /api/timetable for the Android client; 3 — its range=semester;
 // 4 — compression, ETag revalidation, throttled refresh and import limits;
-// 5 — error codes (`code` beside `error`, see server/errors.js), timetable 304 before any work.
-const API_VERSION = 5;
+// 5 — error codes (`code` beside `error`, see server/errors.js), timetable 304 before any work;
+// 6 — the timetable carries the group's exams and credits from other catalog documents.
+const API_VERSION = 6;
 
 // Liveness plus what the server currently reads from the university, without network calls.
 app.get("/api/health", async (_req, res) => {
@@ -118,25 +121,30 @@ app.get("/api/timetable", async (req, res, next) => {
     const calendar = await directoryCalendar();
     const range = req.query.range === "semester" ? "semester" : undefined;
     const today = todayIso();
+    // The group's exams and credits from other documents ("Расписание зачетов"); a server
+    // still building its first index answers without them rather than wait.
+    const idx = readyIndex();
     // The answer follows only from these: the document's version, the parser and the server
     // that read it, the week table, the request and the date. An unchanged one comes back
     // as an empty 304 before the document is opened or a single day is computed.
     const etag = 'W/"tt-' + createHash("sha1")
-      .update([API_VERSION, PARSER_VERSION, file.id, file.modified, calendar?.updatedAt, group, from, req.query.days, range, today].join("|"))
+      .update([API_VERSION, PARSER_VERSION, file.id, file.modified, calendar?.updatedAt, idx?.builtAt, group, from, req.query.days, range, today].join("|"))
       .digest("base64url")
       .slice(0, 22) + '"';
     res.set("ETag", etag);
     if (req.fresh) return res.status(304).end();
+    const schedule = await scheduleFor(file);
     res.json(
       timetable({
         file,
-        schedule: await scheduleFor(file),
+        schedule,
         calendar,
         group,
         from,
         days: req.query.days,
         range,
         today,
+        session: sessionEntriesOf(idx, group, file.faculty || schedule.source.faculty, file.id),
       }),
     );
   } catch (e) {