chore(scanner): remove orphan src/index.js after Index.res rename

The lowercase index.js was the entry point pre-migration. PR #21 (TS strip)
plus the rescript reconcile in 9d663eb introduced Index.res -> Index.mjs as the
package main; the original lowercase file is now unreferenced (no importer in
the workspace).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: hyperpolymath