busy-nudge false-fires on working: sent without re=<ask tag>

stmtBusyNudgeCandidates (hub.mjs:1991) keys its NOT EXISTS on r.sender=original-recipient AND r.re=original-tag; never constrains r.recipient. A working: reply that omits re=<ask tag> never matches, so the ask stays a candidate and the 300s busy-nudge fires despite the agent having signaled. Guide rule 23 (SEEDED_MESSAGE_GUIDE, hub.mjs:2081) MANDATES re= but nothing enforces it. Pre-existing, independent of the worker->PM reroute (Gate 1); surfaced by coder-llmmsgsrv-cc while tracing the reroute's busy-nudge interaction 2026-07-13. Fix options: enforce/auto-attach re= on working: replies, or relax the candidate query.