refactor: replace most custom date util functions by lancet ones

refactor: add precision mode to missing intervals function

routes/compat/wakatime/v1/heartbeat.go

@@ -1,6 +1,7 @@
 package v1
 
 import (
+	"github.com/duke-git/lancet/v2/datetime"
 	"net/http"
 	"time"
 
@@ -65,7 +66,7 @@ func (h *HeartbeatHandler) Get(w http.ResponseWriter, r *http.Request) {
 	}
 
 	timezone := user.TZ()
-	rangeFrom, rangeTo := utils.StartOfDay(date.In(timezone)), utils.EndOfDay(date.In(timezone))
+	rangeFrom, rangeTo := datetime.BeginOfDay(date.In(timezone)), datetime.EndOfDay(date.In(timezone))
 
 	heartbeats, err := h.heartbeatSrvc.GetAllWithin(rangeFrom, rangeTo, user)
 	if err != nil {

routes/compat/wakatime/v1/summaries.go

@@ -2,6 +2,7 @@ package v1
 
 import (
 	"errors"
+	"github.com/duke-git/lancet/v2/datetime"
 	"net/http"
 	"strings"
 	"time"
@@ -120,7 +121,7 @@ func (h *SummariesHandler) loadUserSummaries(r *http.Request) ([]*models.Summary
 	// i.e. for wakatime, an interval 2021-04-29 - 2021-04-29 is actually 2021-04-29 - 2021-04-30,
 	// while for wakapi it would be empty
 	// see https://github.com/muety/wakapi/issues/192
-	end = utils.EndOfDay(end).Add(-1 * time.Second)
+	end = datetime.EndOfDay(end)
 
 	overallParams := &models.SummaryParams{
 		From: start,