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/db/store.go

@@ -593,7 +593,8 @@ func (s *Store) UpdateRPGStats(st *RPGStats) error {
 
 // -- Daily XP --
 
-// UpsertDailyXP inserts or updates the daily XP record for a user/date.
+// UpsertDailyXP inserts or updates the daily XP and work seconds for a user/date.
+// xpEarned and workSeconds are accumulated on conflict.
 func (s *Store) UpsertDailyXP(userID int64, date string, xpEarned, workSeconds int64) error {
 	_, err := s.db.Exec(`
 		INSERT INTO daily_xp (user_id, date, xp_earned, work_seconds)
@@ -605,6 +606,26 @@ func (s *Store) UpsertDailyXP(userID int64, date string, xpEarned, workSeconds i
 	return err
 }
 
+// SetDailyWorkSeconds overwrites the work_seconds for a specific day (used during recalc on edit).
+func (s *Store) SetDailyWorkSeconds(userID int64, date string, workSeconds int64) error {
+	_, err := s.db.Exec(`
+		INSERT INTO daily_xp (user_id, date, xp_earned, work_seconds)
+		VALUES (?, ?, 0, ?)
+		ON CONFLICT(user_id, date) DO UPDATE SET
+			work_seconds = ?
+	`, userID, date, workSeconds, workSeconds)
+	return err
+}
+
+// SumDailyWorkSeconds returns the sum of work_seconds across all days for the user.
+func (s *Store) SumDailyWorkSeconds(userID int64) (int64, error) {
+	var total int64
+	err := s.db.QueryRow(
+		"SELECT COALESCE(SUM(work_seconds), 0) FROM daily_xp WHERE user_id=?", userID,
+	).Scan(&total)
+	return total, err
+}
+
 // GetDailyXP returns the daily XP record for a user/date.
 func (s *Store) GetDailyXP(userID int64, date string) (*DailyXP, error) {
 	row := s.db.QueryRow(`
@@ -890,6 +911,31 @@ func (s *Store) GetUserDaysInRange(userID int64, startDate, endDate string) ([]D
 	return days, rows.Err()
 }
 
+// GetDatesWithEvents returns all distinct dates (from the days table) on which
+// the user has at least one event, ordered ascending.
+func (s *Store) GetDatesWithEvents(userID int64) ([]string, error) {
+	rows, err := s.db.Query(`
+		SELECT DISTINCT d.date
+		FROM days d
+		JOIN events e ON e.day_id = d.id
+		WHERE d.user_id = ?
+		ORDER BY d.date ASC
+	`, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var dates []string
+	for rows.Next() {
+		var date string
+		if err := rows.Scan(&date); err != nil {
+			return nil, err
+		}
+		dates = append(dates, date)
+	}
+	return dates, rows.Err()
+}
+
 // CreateEvent inserts a new event record (typically "in" or "out").
 func (s *Store) CreateEvent(userID int64, dayID int64, eventType string, workTypeID *int64, occurredAt int64, note string) error {
 	_, err := s.db.Exec(