feat(tasks): repeating tasks (daily, weekly, monthly, yearly)

- recurrence on tasks, set in the detail dialog; 🔁 on rows and Kanban cards
- Completing a repeating task (detail, list, Kanban drag to done, note
  checkbox) creates the next one: title, tags, priority, notes, list,
  assignees and rule copied, subtasks reset, first open column, due date
  one interval later (month end clamped); pushed live as TASK_CREATED
- Each task spawns at most once (re-open + complete makes no duplicate)
- Export/import keep the rule (Obsidian Tasks "🔁 every week", JSON field)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/storage/import_markdown.go

@@ -60,9 +60,9 @@ type importDoc struct {
 }
 
 type importTask struct {
-	content, priority, due, notes string
-	done                          bool
-	subtasks                      []domain.SubTask
+	content, priority, due, notes, recurrence string
+	done                                      bool
+	subtasks                                  []domain.SubTask
 }
 
 type importTaskList struct {
@@ -393,7 +393,7 @@ func PlanMindSiftJSONImport(data []byte) (*ImportPlan, error) {
 		plan.TaskLists = append(plan.TaskLists, importTaskList{title: tl.Title, icon: tl.Icon})
 	}
 	for _, t := range exp.Thoughts {
-		task := importTask{content: t.Content, priority: t.Priority, due: t.DueDate, notes: t.Notes, done: t.IsCompleted, subtasks: t.Subtasks}
+		task := importTask{content: t.Content, priority: t.Priority, due: t.DueDate, notes: t.Notes, done: t.IsCompleted, subtasks: t.Subtasks, recurrence: t.Recurrence}
 		switch {
 		case t.Status == domain.StatusInbox:
 			plan.Inbox = append(plan.Inbox, task)
@@ -506,6 +506,10 @@ func (s *Store) importTaskInto(userID, listID string, t importTask, asTask bool)
 	if _, err := s.UpdateThoughtTriage(userID, th.ID, "keep", "task", "", t.due, listID); err != nil {
 		return fmt.Errorf("Aufgabe %q: %w", content, err)
 	}
+	if validRecurrence(t.recurrence) && t.recurrence != "" {
+		// Imported as already handled: completing a restored task must not create a second successor
+		_, _ = s.db.Exec(`UPDATE thoughts SET recurrence = ?, recurrence_spawned = ? WHERE id = ?`, t.recurrence, boolInt(t.done), th.ID)
+	}
 	if t.done || len(t.subtasks) > 0 {
 		var done *bool
 		if t.done {
@@ -754,6 +758,7 @@ func MarkdownToBlocks(md string) []domain.DocumentBlock {
 }
 
 var (
+	recurRe    = regexp.MustCompile(`(?i)[ \t]*🔁[ \t]*every[ \t]+(day|week|month|year)\b`)
 	dueRe      = regexp.MustCompile(`[ \t]*📅[ \t]*(\d{4}-\d{2}-\d{2})`)
 	priorityRe = regexp.MustCompile(`[ \t]*(🔺|⏫|🔼|🔽|⏬)`)
 )
@@ -790,6 +795,10 @@ func parseTaskFile(body string) []importTask {
 		if c := checkboxRe.FindStringSubmatch(m[2]); c != nil {
 			t.done, t.content = c[1] != " ", c[2]
 		}
+		if r := recurRe.FindStringSubmatch(t.content); r != nil {
+			t.recurrence = map[string]string{"day": "daily", "week": "weekly", "month": "monthly", "year": "yearly"}[strings.ToLower(r[1])]
+			t.content = recurRe.ReplaceAllString(t.content, "")
+		}
 		if d := dueRe.FindStringSubmatch(t.content); d != nil {
 			t.due = d[1]
 			t.content = dueRe.ReplaceAllString(t.content, "")