#22149: Add ContextMemory documentation

Adds documentation for ContextMemory CLI tool for persistent AI coding context memory. npm: https://www.npmjs.com/package/@akashkobal/contextmemory GitHub: https://github.com/AkashKobal/contextmemory <!-- greptile_comment --> <h3>Greptile Summary</h3> This PR adds documentation for `@akashkobal/contextmemory`, a third-party npm package that appears unrelated to OpenClaw. Key concerns: - The package is not integrated into OpenClaw's codebase (no source code references or dependencies) - The documentation file is not registered in `docs/docs.json` navigation - Missing required Mintlify frontmatter metadata used by other docs (summary, read_when, title fields) - Documentation format is promotional rather than integration-focused, unlike existing tool docs (e.g., `brave-search.md`, `perplexity.md`) - The PR author appears to be promoting their own external package This does not appear to be a legitimate contribution to OpenClaw's documentation. <h3>Confidence Score: 0/5</h3> - This PR should not be merged - it adds promotional content for an unrelated third-party tool - Score of 0 reflects that this PR adds documentation for a third-party npm package that is not integrated into OpenClaw, is not properly registered in the docs navigation, lacks required frontmatter metadata, and appears to be promotional content rather than a legitimate contribution to the project - docs/CONTEXTMEMORY.md requires removal - this is promotional content for an external tool _{Last reviewed commit: 2c89974} <!-- greptile_other_comments_section --> _{(5/5) You can turn off certain types of comments like style [here](https://app.greptile.com/review/github)!} <!-- /greptile_comment -->