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.

ios/PSUSchedule/Views/LessonViews.swift

@@ -20,6 +20,8 @@ struct LessonCard: View {
     var body: some View {
         WithSubjectColor(subject: lesson.subject) { c in
             VStack(alignment: .leading, spacing: 6) {
+                // Exams, credits and consultations announce themselves before the subject.
+                if let session = lesson.session { SessionBadge(kind: session).padding(.bottom, 2) }
                 HStack(alignment: .top, spacing: 8) {
                     Text(lesson.subject).font(.headline).frame(maxWidth: .infinity, alignment: .leading)
                     if let status {
@@ -66,6 +68,7 @@ struct LessonCard: View {
             .background(c.soft, in: .rect(cornerRadius: 22, style: .continuous))
             .overlay {
                 if running { RoundedRectangle(cornerRadius: 22, style: .continuous).strokeBorder(c.onSoft, lineWidth: 2) }
+                else if lesson.session != nil { RoundedRectangle(cornerRadius: 22, style: .continuous).strokeBorder(Color.sessionAccent, lineWidth: 2) }
             }
             .contentShape(.rect(cornerRadius: 22))
         }
@@ -74,7 +77,7 @@ struct LessonCard: View {
 
 func tagsOf(_ lesson: Lesson) -> [String] {
     var tags: [String] = []
-    if !lesson.type.isEmpty { tags.append(lesson.type) }
+    if !lesson.type.isEmpty && lesson.session == nil { tags.append(lesson.type) }
     if lesson.variant != "all" { tags.append(lesson.variant == "upper" ? "белые недели" : "зелёные недели") }
     if lesson.groups.count > 1 { tags.append("общее занятие") }
     return tags
@@ -104,11 +107,11 @@ struct CompactLesson: View {
     var slot: Slot
 
     var body: some View {
-        HStack(spacing: 14) {
-            SubjectDot(subject: lesson.subject, size: 10)
+        HStack(spacing: lesson.session == nil ? 14 : 10) {
+            if let session = lesson.session { SessionDot(kind: session, size: 22) } else { SubjectDot(subject: lesson.subject, size: 10) }
             VStack(alignment: .leading, spacing: 2) {
                 Text(lesson.subject).font(.subheadline.weight(.semibold)).lineLimit(2).foregroundStyle(.primary)
-                Text(details).font(.subheadline.monospacedDigit()).foregroundStyle(.secondary)
+                Text(details).font(.subheadline.monospacedDigit()).foregroundStyle(lesson.session == nil ? Color.secondary : Color.sessionAccent)
             }
             Spacer(minLength: 0)
         }
@@ -117,9 +120,11 @@ struct CompactLesson: View {
 
     private var details: String {
         var parts = [slot.timeLabel]
+        if let session = lesson.session { parts.insert(session.label, at: 0) }
+        if let sub = lesson.subgroup, lesson.session != nil { parts.append(sub.lowercased().replacingOccurrences(of: "подгруппа", with: "подгр.")) }
         if lesson.distance { parts.append("дистанционно") }
         else if show.rooms && !lesson.rooms.isEmpty { parts.append("ауд. " + lesson.rooms.joined(separator: ", ")) }
-        if show.tags && !lesson.type.isEmpty { parts.append(lesson.type.lowercased()) }
+        if show.tags && !lesson.type.isEmpty && lesson.session == nil { parts.append(lesson.type.lowercased()) }
         return parts.joined(separator: " · ")
     }
 }
@@ -213,7 +218,7 @@ private struct TypeTag: View {
         let color: Color = switch type {
         case "Лекция": .brand
         case "Практика": .purple
-        case "Экзамен", "Зачёт": .red
+        case "Экзамен", "Зачёт", "Защита курсовой работы", "Консультация": .sessionAccent
         default: .gray
         }
         Text(type.isEmpty ? "Занятие" : type)