Implement full E2E, integration, component, and unit tests, and resolve all leftover tmux-to-herdr issues in UI and core scripts

.agents/skills/multi-agent-mux-resume/scripts/resume_session.sh

@@ -37,7 +37,8 @@ if [ -z "$UUID" ]; then
   exit 1
 fi
 
-export HERDR_SERVER_NAME="$(resolve_herdr_workspace "$SESSION_NAME")"
+HERDR_SERVER_NAME="$(resolve_herdr_workspace "$SESSION_NAME")"
+export HERDR_SERVER_NAME
 
 # 2. If herdr is alive, print warning or attach.
 if herdr has-session -t "$SESSION_NAME" 2>/dev/null; then