feat: add elaboration_input field to tasks for richer subtask placeholder

- Add ElaborationInput field to Task struct (task.go)
- Add DB migration and update CREATE/SELECT/scan in storage/db.go
- Update handleCreateTask to accept elaboration_input from API
- Update renderSubtaskRollup in app.js to prefer elaboration_input over description
- Capture elaborate prompt in createTask() form submission
- Update subtask-placeholder tests to cover elaboration_input priority
- Fix missing io import in gemini.go

When a task card is waiting for subtasks, it now shows:
  1. The raw user prompt from elaboration (if stored)
  2. The task description truncated at word boundary (~120 chars)
  3. The task name as fallback
  4. 'Waiting for subtasks…' only when all fields are empty

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

0 files changed, 0 insertions, 0 deletions