fix(openclaw): add auto-recall short query threshold

[cnYui]

Closes #1347

Summary

• Add recall.autoRecallMinQueryLength for memos-local-openclaw auto-recall.
• Default the threshold to 2 to preserve existing behavior.
• Skip auto-recall search when the normalized prompt is shorter than the configured threshold.
• Document setting the threshold to 10 for short acknowledgements.

Tests

• npm test -- tests/auto-recall-min-query-length.test.ts tests/config.test.ts
• npm run build