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.sh

@@ -10,7 +10,8 @@
 #
 # IMPORTANT: Check stop_hook_active to avoid infinite loops.
 
-set -euo pipefail
+# Intentionally omit -e so the reminder always emits even if session_stats fails.
+set -uo pipefail
 
 if [ -n "${MEM0_DEBUG:-}" ]; then
   mkdir -p "$HOME/.mem0" && exec 2>>"$HOME/.mem0/hooks.log"