chore: remove stale stx-router-inline partial

Dead code — old copy-pasted router that intercepted all <a href> clicks.
The canonical router is auto-injected by stx via injectRouterScript()
and only intercepts [data-stx-link] elements.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: glennmichael123