fix: correct template filename and remove non-existent testutils dir from docs

[namedfarouk]

What this fixes

Two documentation inconsistencies found while setting up the project locally:

1. CLAUDE.md referenced analyst_agent.jinja2 as a template file,
   but the actual filename in templates/ is analytics_agent.jinja2.
   This would confuse developers following the guide.

2. README.md listed testutils/ as an existing directory in the
   architecture overview, but this directory does not exist in the repo.
   Removed to keep docs accurate.

How I verified

Cloned the repo locally, ran ls templates/ and ls to verify all
actual filenames and directories against the documentation.