feat: publish standalone worker

Separate worker packaging and service lifecycle from the control plane.

internal/workdays/workdays.go

@@ -0,0 +1,54 @@
+// Package workdays provides functionality.
+package workdays
+
+import (
+	"strconv"
+	"time"
+
+	"github.com/rickar/cal/v2"
+)
+
+// NewHoliday provides functionality.
+func NewHoliday(month time.Month, day int) *cal.Holiday {
+	return &cal.Holiday{
+		Name:  month.String() + " " + strconv.Itoa(day),
+		Month: month,
+		Day:   day,
+		Func:  cal.CalcDayOfMonth,
+	}
+}
+
+// GetCalendar provides functionality.
+func GetCalendar() *cal.BusinessCalendar {
+	c := cal.NewBusinessCalendar()
+
+	// add holidays for the business
+	c.AddHoliday(
+		NewHoliday(time.January, 1),
+		NewHoliday(time.January, 2),
+		NewHoliday(time.January, 3),
+		NewHoliday(time.January, 4),
+		NewHoliday(time.January, 5),
+		NewHoliday(time.January, 6),
+		NewHoliday(time.January, 7),
+		NewHoliday(time.January, 8),
+		NewHoliday(time.February, 23),
+		NewHoliday(time.March, 8),
+		NewHoliday(time.May, 1),
+		NewHoliday(time.May, 9),
+		NewHoliday(time.June, 12),
+		NewHoliday(time.November, 4),
+		NewHoliday(time.December, 30),
+		NewHoliday(time.December, 31),
+	)
+
+	// optionally change the holiday calculation behavior
+	// (the default is US-style where weekend holidays are
+	// observed on the closest weekday)
+	// c.Observed = cal.ObservedExact
+
+	c.SetWorkday(time.Saturday, true)
+	c.SetWorkday(time.Sunday, true)
+
+	return c
+}