DIS-021: wpush debug spew on by default; pack built on error; have-set unused

The wire-push path ships loud debug and wastes work. Every wpush: / wpush_dump: line is an unconditional fprintf(stderr,…) (keeper/WIRECLI.c:1072,1108,1139,1597,1650,1699…) — leftover instrumentation that prints all 265 objects on every push. The full pack is built BEFORE the refname/negotiation is validated, so a rejected push still pays the pack cost. have_peer=0 is printed while peer_tips=4 (a mislabel), and the have-set ("has 2349 objects") does not prune the commit walk — the full 265-object pack is sent even when the peer already has most of it. Goals: silent by default, no pack on error, incremental packs. See PackLog, Keeper.

Issues

Three independent defects in keeper/WIRECLI.c, all in the push path.

Debug spew: wpush:/wpush_dump: fprintf unconditional — must be ABC_TRACE-gated.
Pack-before-validate: wire_push_inner builds the pack, then send_update; a funny-ref/non-FF reject wastes the whole build.
have_peer=0 with peer_tips=4 (:1597) is self-contradictory; the have-set is built (:1650) but the walk is not pruned by it.

Blockers

None.

Planned

Gate the noise, reorder validation before the pack, and use the have-set.

Wrap every wpush:/wpush_dump: fprintf in ABC_TRACE (or a trace helper) so a normal push is silent.
Validate the refname + run the FF/peer check up front; build/send the pack ONLY when the update will be accepted (no pack on error).
Prune the object walk by the have-set so an incremental push sends only objects the peer lacks; fix the have_peer/peer_tips flag.
Tests: a rejected push builds no pack; an up-to-date incremental push sends a near-empty pack; no wpush output without ABC_TRACE.