fix: dedupe solid-js to a single version in lockfile

The tests app resolved solid-js 1.9.9 while @solidjs/start's deps
(vite-plugin-solid, terracotta) resolved 1.9.11, bundling two Solid
runtimes and crashing client hydration in production builds. This
broke 13 Cypress e2e tests in CI since #2074.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: brenelz