fix(attach): hints print the row's attach_command (Issue #72, comments 926/930, U1)

create's closing hint, the delegate-job wrapper's dispatch hint and stop's
stuck-TUI message printed the pre-#71 forms (`herdr session attach <name>`,
`HERDR_SESSION_NAME=... herdr agent attach <name>`), which miss an agent whose
name is over 32 characters or has upper case. They now print the session row's
attach_command, or lib_py.agents.sanitize.attach_command(server, name) when
there is no row (lib.sh session_attach_command). deploy/INSTALL.md and
install_mam.sh show the `herdr --session <server> agent attach <herdr name>`
form.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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

@@ -332,7 +332,7 @@ if [ "$PURGE" = "1" ] && [ "$HERDR_ALIVE" = "1" ]; then
   if herdr has-session -t "$SESSION_NAME" 2>/dev/null; then
     echo "ERROR: session '$SESSION_NAME' is still alive after the kill chain." >&2
     echo "  Refusing registry removal — records preserved (no state was modified)." >&2
-    echo "  Diagnose the stuck TUI (herdr session attach '$SESSION_NAME'), then re-run" >&2
+    echo "  Diagnose the stuck TUI ($(session_attach_command "$SESSION_NAME" "${HERDR_SESSION_NAME:-default}")), then re-run" >&2
     echo "  stop_session.sh --purge-conversation --yes (retry is safe/idempotent)." >&2
     delegate_publish_event "$DELEGATE_JOB_ID" cancelled "purge aborted: session still alive; no state was modified" "$DELEGATE_JOB_TOKEN" "$DELEGATE_JOB_ATTEMPT"
     exit 4