Adds a flag on tasks to distinguish manual completions from the
cascade auto-completion performed by complete_subtask_and_check_parent.
Partial index on (done_at, auto_completed) supports the Phase 8
daily-count query without bloating the tasks index footprint.
Forward-only: pre-migration completed rows default to 0 (they count).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Jake
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