Add habit HTTP endpoints

- Create DTOs for HTTP requests and responses
- Implement habit handlers (create, get today's, mark)
- Register routes in router: POST /habits, GET /habits/today, POST /habits/{id}/mark
- Add missing repository methods (FindByID, FindByHabitID, FindPendingByHabitID, Delete)
- Wire up dependencies in main.go
- Tested with curl: create, list, mark habits work correctly

internal/infrastructure/http/dto.go

@@ -0,0 +1,47 @@
+package http
+
+import "time"
+
+type CreateHabitRequest struct {
+	Name          string   `json:"name"`
+	Description   string   `json:"description"`
+	Type          string   `json:"type"`
+	Frequency     string   `json:"frequency"`
+	SpecificDays  []int    `json:"specific_days,omitempty"`
+	SpecificDates []int    `json:"specific_dates,omitempty"`
+	CarryOver     bool     `json:"carry_over"`
+	TargetValue   *float64 `json:"target_value,omitempty"`
+}
+
+type HabitResponse struct {
+	ID            string     `json:"id"`
+	UserID        string     `json:"user_id"`
+	Name          string     `json:"name"`
+	Description   string     `json:"description"`
+	Type          string     `json:"type"`
+	Frequency     string     `json:"frequency"`
+	SpecificDays  []int      `json:"specific_days,omitempty"`
+	SpecificDates []int      `json:"specific_dates,omitempty"`
+	CarryOver     bool       `json:"carry_over"`
+	TargetValue   *float64   `json:"target_value,omitempty"`
+	CreatedAt     time.Time  `json:"created_at"`
+	ArchivedAt    *time.Time `json:"archived_at,omitempty"`
+}
+
+type MarkHabitRequest struct {
+	ScheduledDate string   `json:"scheduled_date"`
+	Value         *float64 `json:"value,omitempty"`
+}
+
+type TodaysHabitResponse struct {
+	ID            string    `json:"id"`
+	Name          string    `json:"name"`
+	Type          string    `json:"type"`
+	TargetValue   *float64  `json:"target_value,omitempty"`
+	ScheduledDate time.Time `json:"scheduled_date"`
+	IsCarriedOver bool      `json:"is_carried_over"`
+}
+
+type ErrorResponse struct {
+	Error string `json:"error"`
+}