After daemon auto-export, JSONL mtime could be newer than database mtime
due to SQLite WAL mode not updating beads.db until checkpoint. This caused
validatePreExport to incorrectly block subsequent exports with "JSONL is
newer than database" error, leading to daemon shutdown.
Solution: Call TouchDatabaseFile after all export operations to ensure
database mtime >= JSONL mtime. This prevents false positives in validation
When 'bd sync --import-only' completes, it imports JSONL changes into
the database but doesn't update the database file's modification time.
This causes 'bd doctor' to incorrectly warn that 'JSONL is newer than
database' even when they're in sync.
Root cause: SQLite in WAL mode writes to beads.db-wal; the main beads.db
mtime often doesn't change until a checkpoint. bd doctor compares JSONL
mtime to beads.db mtime, so it can misfire without an mtime bump.
The fix adds touchDatabaseFile() that:
- Only runs when import actually made changes (not dry-run, not unchanged)
- Sets DB mtime to max(JSONL mtime, now) + 1ns to handle clock skew
- Is best-effort (logs warning on failure, doesn't fail import)
- Includes tests for basic touch and clock skew scenarios
Fixes: bd-g3ey
