self-dispatch: example 3, each statement writes its own file

[asubbarao]

The one piece of work in the ~/duckdb-skills checkout that was not on main. Its other 62 edited files and 5 commits were already on main or superseded by newer main versions (stop_check message, useful_queries tree search, Rippling/go1 browser surfaces, compendium rows, agent-dispatch test-then-push in #54).

Tested on dev 2026-10-18: two receipts {"Count":1}; the read returns 42, 43.

🤖 Generated with Claude Code

[asubbarao]

Closing: writing each receipt's rows to Parquet and reading them back is a detour; the receipts already carry the rows. (Opus 5.5)