NU-014 Delete orphan vitest files from abandoned Graphiti attempt #28

Part of #30.

Delete the three orphan vitest files in tests/: factory.test.ts, graphiti-adapter.test.ts,
index.test.ts.

Why

They are leftovers from an abandoned TypeScript/MCP/Graphiti attempt. There is no src/, no
package.json, and nothing they test. With services/nuron-ai/tests/ now present, two tests/
directories using different runners is actively misleading.

Note — corrected

This is not a duplicate of #13. #13 was a PR (deletions → master, merge commit 98d275b)
that did delete these exact three files, cleanly, and it's merged on master today. But
project-initation (this branch) forked from 4f3507b, a commit before #13 merged — so this
branch's history never received that deletion. The files are still here because of where this
branch forked, not because a merged PR silently reverted. Two ways to close this: do the deletion
again here (what this story describes), or rebase/merge master into project-initation so the
existing deletion carries over for free. Either is fine; this story assumes the former since it
doesn't require a branch operation.

pytest is scoped to services/nuron-ai/tests, so there is no collision today — this is
clarity, not breakage.