refactor: restore stored aggregates with incremental update on edit

- Restore TotalWorkSeconds, CurrentStreak, LongestStreak writes in
  computeAndAwardXP and updateStreak (incremental on clock out)
- Add recalcDayWorkSeconds and recalcAggregates for event edit path
  (recompute day + total + streak from scratch when events change)
- Call recalcAggregates after editEventTimeSet, deleteEventConfirm,
  addEventDo in calendar.go
- Remove runtime computeStreaks and totalWorkSeconds (N+1 scan)
  from RPG display, burnout, and clockOut
- Add SetDailyWorkSeconds, SumDailyWorkSeconds store methods
- Clean up unused dead functions and dead code in rpg.go

internal/bot/clock.go

@@ -70,10 +70,10 @@ func (h *Handler) clockOut(chatID int64) (string, error) {
 		today := now.Format(DateLayout)
 		isWeekend := now.Weekday() == time.Saturday || now.Weekday() == time.Sunday
 
-		streak, _ := h.updateStreak(user.ID, today, true)
-		xp, leveledUp, newLevel, _ := h.computeAndAwardXP(user.ID, sessionWork, streak, today)
 		stats, _ := h.DB.GetOrCreateRPGStats(user.ID)
-		totalHours := float64(h.totalWorkSeconds(user.ID, loc)) / secondsPerHour
+		h.updateStreak(stats, user.ID, today)
+		xp, leveledUp, newLevel, _ := h.computeAndAwardXP(stats, user.ID, sessionWork, stats.CurrentStreak, today)
+		totalHours := float64(stats.TotalWorkSeconds) / secondsPerHour
 		unlocked := h.checkAchievements(user.ID, stats, sessionWork, today, isWeekend, totalHours)
 
 		text += fmt.Sprintf("\n\n+%d XP (Lv.%d)", xp, newLevel)