c99a4a2d95
- Add filter.go: Parse filters (+tag, -tag, attribute:value, IDs) - Implement Filter.ToSQL() for WHERE clause generation - Add modifier.go: Parse modifiers (set/clear attributes, add/remove tags) - Implement Modifier.Apply() to update existing tasks - Add dateparse.go: Smart date parsing (ISO, today, tomorrow, weekdays) - Implement nextWeekday logic (smart Sunday interpretation) - Update GetTasks() to accept Filter parameter - Add CreateTaskWithModifier() for task creation with modifiers - Add comprehensive test suite (13 new tests, all passing) - Support filtering by status, project, priority, tags, UUIDs, display IDs - Support modifying priority, project, dates, recurrence, tags