Add robust date parsing and simplify lesson selection logic. Introduces ISO8601 formatters (with and without fractional seconds) and updates parseNextSchoolDayDate to try both variants, plus existing yyyy-MM-dd fallback. Adds LessonCandidate, startOfDay and nextSchoolDay helpers and builds a sorted candidate list (today, tomorrow, next school day) to pick the appropriate lesson set and correctly set isNextDay/isNextSchoolDay flags. Cleans up previous branching-heavy logic and improves handling of edge cases (lessons finished, next-school-day resolution).
Several watch UI and sync improvements: clamp CountdownRing values and use clamped values for progress/color/display; add optional backgroundColor to FirkaCard and refactor HomeView to use lessonTitleWithStatus, lessonCardBackgroundColor and improved break time calculation and refresh handling (onChange of lastUpdated). TimetableView now shows status icons/colors via helper methods. DataStore now returns a localized "time_now" for recent updates. WatchSessionManager handles Flutter channel/unready states by serving shared language state when available and avoids empty language replies. Dart fixes: await initLang in settings, return null from WatchSyncHelper when uninitialized, and attempt to publish language to watch after initialization in main.
