Invert the delivery verdict from negative to positive evidence. Previously,
success was declared by the ABSENCE of a draft snippet on a prompt line: if
the `❯|^>|│ >` glyph matched nothing (busy-receiver draft on an unmatched
line, or wrong-pane drift), an UNSUBMITTED message read as "✓ delivered"
exit 0 — a silent worker->lead relay stall (filed by UC-LEAD, PR #3046:
three review verdicts reported delivered but never surfaced for ~50 min).
Fix: success now requires POSITIVE evidence — either the queued banner, or
the REPL input box located AND clear of the message tail. If the input box
cannot be located, status is `unconfirmed` -> exit 2 + stderr ("could not
confirm submission ... may be UNDELIVERED"). The near-dead `*)` indeterminate
default also flips from silently returning 0 to exit 2. Bracketed-paste and
double-Enter delivery mechanics are unchanged; queued/draft/delivered
semantics are preserved, only the failure-mode default direction changes.
Adds `test-send-message-verdict.sh`: 3 real tmux-pane fixtures (delivered /
unconfirmed-glyphless / draft) locking the fail-loud verdict logic, and
upgrades `test-send-message-socket.sh` fixtures from a glyphless bash prompt
to `❯`-prompt REPLs so the patched binary can read delivery positively.
Reproduce-first evidence (baseline vs patched, glyphless-pane fixture):
baseline: rc=0, stdout "✓ delivered to =noglyph" (silent false positive)
patched: rc=2, stderr "could not confirm submission ... may be UNDELIVERED"
Test results after port:
test-send-message-verdict.sh -> PASS=3 FAIL=0
test-send-message-socket.sh -> ok
Firewall: grep -niE 'jason|woltje|jarvis' on changed files = 0 hits;
tools/quality/scripts/verify-sanitized.sh -> sanitization gate passed.
shellcheck: 1 pre-existing SC2034 finding (unused loop var `attempt`,
present identically in baseline) carried through; 0 new findings.
Part of #891
