TestManualCleanRepro replays a real device highlight export through the
same conversion path the sync handler uses, diffs the output against
the CFIs stored at ingest time, and computes a ground-truth oracle by
locating each selection in the flattened document itself. Classifies
every row as healthy / diff-base / backwards for both the converter
and the stored data. Skips automatically when fixture files are not
present on the machine (manual test, like cfi_verify_manual_test.go).
REPRO_VERBOSE=1 prints per-row detail; REPRO_EMIT_SQL=<path> emits
idempotent UPDATE statements that heal database rows written by the
old converter from the preserved raw device positions - used to
backfill dev and validated against production data.
