feat: Add OpenClaw-native Memoria onboarding

[randomradio]

Summary

• add OpenClaw-native openclaw memoria install and openclaw memoria verify flows for the memory-memoria plugin
• harden the plugin installer/verifier around current OpenClaw config validation, linked plugin discovery, and embedded-mode env handling
• update the OpenClaw plugin README to document the plugin-install-first onboarding path

Validation

• installed the plugin via openclaw plugins install --link /home/momo/src/Memoria-plugins/plugins/openclaw
• ran openclaw plugins enable memory-memoria
• ran MEMORIA_DB_URL=mysql://root:111@127.0.0.1:6001/memoria MEMORIA_EMBEDDING_PROVIDER=mock MEMORIA_EMBEDDING_MODEL=mock MEMORIA_EMBEDDING_API_KEY=dummy MEMORIA_EMBEDDING_DIM=1536 openclaw memoria install --memoria-bin /usr/local/bin/memoria --skip-memoria-install
• ran openclaw memoria verify
• verified embedded deep checks reached openclaw memoria stats and openclaw ltm list