refactor: move types out of app.go into types/, renamed module files

types/common.go

@@ -0,0 +1,22 @@
+package types
+
+import "time"
+
+// DurationString represents a duration, such as "2s" or "24h".
+// See https://pkg.go.dev/time#ParseDuration for all valid time units.
+type DurationString string
+
+// TimeString is a 24-hr format time "HH:MM" such as "07:30".
+type TimeString string
+
+// TimeRange represents a time range with start and end times.
+type TimeRange struct {
+	Start time.Time
+	End   time.Time
+}
+
+// Item represents a priority queue item with a value and priority.
+type Item struct {
+	Value    interface{}
+	Priority float64
+}