Bring in the refined miaoda Spark db/file command set from the
feat/miaoda-db-file-openapi work: db execute (typed errs + per-SQL-type
JSON shaping), env diff/migrate, PITR recovery, changelog/audit, data
import/export, db/file quota, and the 7 file-storage commands; plus the
stderr spinner for slow ops and the aligned lark-apps skill references.
Resolved overlap with the integration branch's earlier db-execute
iteration (took the refined typed-error version), unified the stderr-TTY
flag on IOStreams.StderrIsTerminal, and combined the shortcut registry
(43 commands total).
f334cc9b34