POST-018: post/put confirmations through the shared banner

be post and be put print their confirmations as raw fprintf to stderr — sniff: commit <hex>, N change(s), staged N put row(s), and the post ambiguous-message picker — bypassing the shared ROWS state banner (BE-005). Route them through ROWS so post/put speak the same banner + --tlv model as get/status.

Input

Context

be post commit confirmation is fprintf(stderr, "sniff: commit <hex>")
(SNIFF.exe.c:815); dry-run already uses ROWS (POST.c:2338).
be put only prints sniff: staged %u put row(s) (PUT.c:1027); its
per-file staged rows already stream via ROWS (PUT.c:712).
Post msg-picker lists candidates with raw fprintf (POST.c:2439/2447).
N change(s) summary tail (POST.c:2345) is a trailing stderr line.

Goals

be post emits a commit ROWS row (verb=post, clickable
commit:?<sha> — ROWS_NAV_COMMIT already exists) under the banner.
be put confirmation rides the same banner (count in the banner /
summary tail), not a bare stderr line.
The ambiguous-message picker renders as banner rows, not raw tabs.

Constraints

Depends on the BE-005 ROWS banner core. sniff/ only; no abc/.
Keep genuine error/diagnostic chatter on stderr — only the report
(data) lines move to the hunk stream.

WIP

Design decisions

Reuse ROWSu8bFeedRec with ROWS_NAV_COMMIT (the tested
?<sha>#<subject> row) for the commit confirmation.
Put's count becomes the banner/summary, mirroring status's tail.

TODOs

Repro: be post/be put emit a banner-headed hunk (commit row /
staged rows) in color & --tlv; no raw stderr report line.
SNIFF.exe.c:815: commit confirmation → ROWS commit row.
PUT.c:1027: staged count → banner/summary, not bare stderr.
Post msg-picker (POST.c:2439) → banner rows.
ctest -j16 green.

Blockers and bummers

None yet.

Outcome

(pending land)