feat: add parse endpoint, refactor recurring tasks, and improve web task completion

Extract CreateRecurringTask into engine package for reuse by both CLI
and API. Add POST /tasks/parse endpoint for CLI-style input parsing.
Remove FK constraint on change_log to preserve history after task
deletion. Update web frontend to filter completed tasks from view and
add mock mode support for development.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

opal-task/cmd/add.go

@@ -4,10 +4,8 @@ import (
 	"fmt"
 	"os"
 	"strings"
-	"time"
 
 	"git.jnss.me/joakim/opal/internal/engine"
-	"github.com/google/uuid"
 	"github.com/spf13/cobra"
 )
 
@@ -101,99 +99,13 @@ func parseAddArgs(args []string) (string, []string, error) {
 }
 
 func addRecurringTask(description string, mod *engine.Modifier) error {
-	// Extract recurrence pattern
-	recurPattern := mod.SetAttributes["recur"]
-	if recurPattern == nil {
-		return fmt.Errorf("no recurrence pattern specified")
-	}
-
-	// Validate: recurring tasks must have due date
-	if mod.SetAttributes["due"] == nil {
-		return fmt.Errorf("recurring tasks require a due date (use due:YYYY-MM-DD or due:monday)")
-	}
-
-	duration, err := engine.ParseRecurrencePattern(*recurPattern)
+	instance, err := engine.CreateRecurringTask(description, mod)
 	if err != nil {
-		return fmt.Errorf("invalid recurrence pattern: %w", err)
+		return err
 	}
 
-	// Create template task (without saving yet)
-	now := time.Now()
-	template := &engine.Task{
-		UUID:               uuid.New(),
-		Status:             engine.StatusRecurring,
-		Description:        description,
-		Priority:           engine.PriorityDefault,
-		Created:            now,
-		Modified:           now,
-		RecurrenceDuration: &duration,
-		Tags:               []string{},
-	}
-
-	// Create modifier without the recur attribute
-	tempMod := &engine.Modifier{
-		SetAttributes:  make(map[string]*string),
-		AttributeOrder: []string{},
-		AddTags:        mod.AddTags,
-		RemoveTags:     mod.RemoveTags,
-	}
-
-	// Copy all attributes except recur
-	for _, key := range mod.AttributeOrder {
-		if key != "recur" {
-			val := mod.SetAttributes[key]
-			tempMod.SetAttributes[key] = val
-			tempMod.AttributeOrder = append(tempMod.AttributeOrder, key)
-		}
-	}
-
-	// Apply modifiers to template before first save
-	if err := tempMod.ApplyToNew(template); err != nil {
-		return fmt.Errorf("failed to apply modifiers to template: %w", err)
-	}
-
-	// Save template
-	if err := template.Save(); err != nil {
-		return fmt.Errorf("failed to save template: %w", err)
-	}
-
-	// Add tags to template (requires task.ID from save)
-	for _, tag := range mod.AddTags {
-		if err := template.AddTag(tag); err != nil {
-			return fmt.Errorf("failed to add tag to template: %w", err)
-		}
-	}
-
-	// Create first instance
-	instance := &engine.Task{
-		UUID:        uuid.New(),
-		Status:      engine.StatusPending,
-		Description: description,
-		Priority:    template.Priority,
-		Created:     now,
-		Modified:    now,
-		ParentUUID:  &template.UUID,
-		Due:         template.Due,
-		Wait:        template.Wait,
-		Scheduled:   template.Scheduled,
-		Project:     template.Project,
-		Tags:        []string{},
-	}
-
-	if err := instance.Save(); err != nil {
-		return fmt.Errorf("failed to save first instance: %w", err)
-	}
-
-	// Copy tags to instance
-	for _, tag := range template.Tags {
-		if err := instance.AddTag(tag); err != nil {
-			return fmt.Errorf("failed to add tag to instance: %w", err)
-		}
-	}
-
-	fmt.Printf("Created recurring task %s\n", template.UUID)
+	fmt.Printf("Created recurring task %s\n", *instance.ParentUUID)
 	fmt.Printf("First instance: %s\n", instance.UUID)
-	fmt.Printf("Recurrence: %s\n", engine.FormatRecurrenceDuration(duration))
 
 	return nil
 }