docs(web-components-vite): document Stencil import injection for static builds

[harshit-d3v]

Summary

• document the Stencil configuration needed for static Storybook builds when using @storybook/web-components-vite
• explain that projects using defineCustomElements() from the generated loader need import injection enabled so Vite includes lazy-loaded component entry files
• add the Stencil 4.26+ config example using �xtras.enableImportInjection
• mention �xperimentalImportInjection for older Stencil versions

Relates to #25704.

Testing

• validated the updated documentation files in the editor
• docs-only change