Extend the plugin memory SPI with a three-arg prefetch(agentId, userQuery, ownerKey) default method and forward ownerKey through PluginMemoryBridge, enabling per-owner isolated recall for external providers. Ship mateclaw-plugin-mem0: an optional, zero-extra-dependency plugin that bridges a self-hosted Mem0 service (semantic recall via /memories/search/, async turn sync via /memories/) with full fault isolation — not part of the default stack. Includes 42 tests and bilingual user docs.
