feat: allow editing frequency and target_value on habits

- Add frequency to UpdateHabitRequest (was immutable, now editable)
- Validate frequency + specific_days/dates coherence on update
- Keep type and is_negative immutable (they change entry semantics)
- Remove completion_rate references from swagger and README

internal/application/commands/update_habit.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"apocapoc-api/internal/domain/repositories"
+	"apocapoc-api/internal/domain/value_objects"
 	"apocapoc-api/internal/shared/errors"
 )
 
@@ -13,10 +14,11 @@ type UpdateHabitCommand struct {
 	UserID        string
 	Name          string
 	Description   string
-	CarryOver     bool
-	TargetValue   *float64
+	Frequency     value_objects.Frequency
 	SpecificDays  []int
 	SpecificDates []int
+	CarryOver     bool
+	TargetValue   *float64
 }
 
 type UpdateHabitHandler struct {
@@ -34,6 +36,18 @@ func (h *UpdateHabitHandler) Handle(ctx context.Context, cmd UpdateHabitCommand)
 		return errors.ErrInvalidInput
 	}
 
+	if !cmd.Frequency.IsValid() {
+		return errors.ErrInvalidInput
+	}
+
+	if cmd.Frequency == value_objects.FrequencyWeekly && len(cmd.SpecificDays) == 0 {
+		return errors.ErrInvalidInput
+	}
+
+	if cmd.Frequency == value_objects.FrequencyMonthly && len(cmd.SpecificDates) == 0 {
+		return errors.ErrInvalidInput
+	}
+
 	habit, err := h.habitRepo.FindByID(ctx, cmd.HabitID)
 	if err != nil {
 		return err
@@ -49,10 +63,11 @@ func (h *UpdateHabitHandler) Handle(ctx context.Context, cmd UpdateHabitCommand)
 
 	habit.Name = cmd.Name
 	habit.Description = cmd.Description
-	habit.CarryOver = cmd.CarryOver
-	habit.TargetValue = cmd.TargetValue
+	habit.Frequency = cmd.Frequency
 	habit.SpecificDays = cmd.SpecificDays
 	habit.SpecificDates = cmd.SpecificDates
+	habit.CarryOver = cmd.CarryOver
+	habit.TargetValue = cmd.TargetValue
 
 	return h.habitRepo.Update(ctx, habit)
 }