Context file resources improvements

The MCP server serves non-existent files as resources. For instance, we can add a missing `CLAUDE.md` file, it will result in this exception's text being included as file content.

I suggest these steps for improvements (note: the following is hand-typed, not AI-generated :-) ):

1. Have a folder for AI contexts so that the user does not have to follow the current convention and can have its own filenames. e.g. `ai-context/UIX.md`.
2. Have `CLAUDE.md` and `ai-context/` be the default green-list of resources to serve.
3. Have a background process watch for changes for the files and file patterns in the above green-list, and inform the AI when they change (documentation at https://modelcontextprotocol.io/docs/concepts/resources#resource-updates).