fix: improve memos local plugin OpenClaw behavior

[hijzy]

Summary

• Add text content alongside structured details for OpenClaw memory tools so newer MCP plugin-tool bridges can display results.
• Preserve keyword fallback retrieval through namespace-wrapped repos and cover it with an OpenClaw e2e test.
• Package the OpenClaw plugin manifest and extend the default Memory Viewer readiness wait to 60s.

Test plan

• Not run locally; changes were committed from the existing working tree as requested.