fix(mem0-plugin): review fixes — loop guard, v3 response format, robustness

- on_stop_cursor.sh: add loop_count guard to prevent infinite re-entry
- on_stop.sh: drop set -e so stats failure doesn't kill the reminder
- _identity.py: fix fallback stub signatures to match production (accept cwd arg)
- on_pre_compact.py: add missing infer=False on session_state writes
- on_session_start.sh: handle v3 search response format (dict with results key)
- Align all plugin versions to 0.2.1 (Claude Code, Codex, Cursor)

mem0-plugin/scripts/on_stop_cursor.sh

@@ -19,6 +19,14 @@ SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 
 INPUT=$(cat)
 
+# Guard against infinite loops: if this is a re-entry after a prior followup,
+# let the turn end. Cursor exposes loop_count in the input JSON.
+LOOP_COUNT=$(echo "$INPUT" | jq -r '.loop_count // 0' 2>/dev/null || echo "0")
+if [ "$LOOP_COUNT" -gt 1 ]; then
+  echo '{}'
+  exit 0
+fi
+
 # Session-end report (best-effort)
 REPORT=$(python3 "$SCRIPT_DIR/session_stats.py" report 2>/dev/null || echo "")
 REPORT_BLOCK=""