perf(skills): optimize sleeps and modularize duplication with multi-agent consensus PASS

- OP-1: Implement reactive _wait_session_gone in lib.sh and stop_session.sh with set -e || true guard
- OP-2: Event-driven MQTT subscribe handshake with sub_pid liveness in delegate-job
- OP-3: Replace CPU time.sleep(0.5) spin with threading.Event wait in reconcile.sh
- OP-4: Define mam_tmux dispatcher targeting resolved _REAL_TMUX_PATH to prevent recursion
- OP-6 & OP-7: Add token variables and bash version source check in lib.sh
- Integrate approved optimization plan and PASS review reports from all agents

.agents/skills/multi-agent-mux-stop/scripts/stop_session.sh

@@ -190,14 +190,14 @@ graceful_stop() {
   esac
   echo "graceful: send-keys '$exitkey' to $SESSION_NAME"
   send_keys_safe "$SESSION_NAME" "$exitkey" "stop$$" || echo "graceful: safe delivery failed (rc=$?) — falling back to kill chain"
-  sleep 3
+  _wait_session_gone "$SESSION_NAME" 5 || true
   if ! tmux has-session -t "$SESSION_NAME" 2>/dev/null; then
     echo "graceful: exited cleanly"
     return 0
   fi
   echo "graceful: still alive → kill-session (SIGTERM)"
   tmux kill-session -t "$SESSION_NAME" 2>/dev/null || true
-  sleep 5
+  _wait_session_gone "$SESSION_NAME" 8 || true
   if ! tmux has-session -t "$SESSION_NAME" 2>/dev/null; then
     echo "graceful: terminated after kill-session"
     return 0