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/domain/models.go

@@ -183,7 +183,8 @@ type Thought struct {
 	KanbanStatus   string        `json:"kanbanStatus,omitempty"` // todo | in_progress | done
 	Notes          string        `json:"notes,omitempty"`
 	Subtasks       []SubTask     `json:"subtasks"`
-	Assignees      []string      `json:"assignees"` // user IDs; only people with access to the task list
+	Assignees      []string      `json:"assignees"`            // user IDs; only people with access to the task list
+	Recurrence     string        `json:"recurrence,omitempty"` // "" | daily | weekly | monthly | yearly
 	AlarmSent      bool          `json:"alarmSent,omitempty"`
 	SortOrder      int           `json:"sortOrder"`
 	CreatedAt      string        `json:"createdAt"`