Add Missing updated_at Column to Subtasks Table

[foxintheloop]

Problem

The subtasks table in packages/shared/src/schema.sql (lines 99-106) has created_at but no updated_at column. All other tables (tasks, goals, lists) have both timestamps, making subtasks inconsistent.

Solution

1. Add updated_at TEXT DEFAULT (datetime('now')) column to subtasks table
2. Add trigger to auto-update on changes:

CREATE TRIGGER IF NOT EXISTS trg_subtasks_updated_at
AFTER UPDATE ON subtasks
BEGIN
  UPDATE subtasks SET updated_at = datetime('now') WHERE id = NEW.id;
END;

3. Update shared types to include updated_at on Subtask

Files

• packages/shared/src/schema.sql — add column and trigger
• packages/shared/src/index.ts — update Subtask type