Track jsx-runtime compatibility for remaining shim .tsx modules

[liuxiaopai-ai]

Following review feedback on #45: while error-boundary.tsx is fixed, several other shim modules still rely on JSX transform assumptions and may hit the same react/jsx-runtime named-export mismatch in specific packaging setups.

Candidate files called out in review:

• packages/vinext/src/shims/link.tsx
• packages/vinext/src/shims/metadata.tsx
• packages/vinext/src/shims/legacy-image.tsx
• packages/vinext/src/shims/form.tsx
• packages/vinext/src/shims/document.tsx
• packages/vinext/src/shims/image.tsx

Proposed follow-up:

1. Decide whether to normalize these shims to React.createElement style, or
2. Fix at plugin level (@vitejs/plugin-rsc) so JSX transform remains robust regardless of user tsconfig/package interop.

I can follow up with a focused PR once direction is confirmed.

[liuxiaopai-ai]

Opened follow-up implementation PR: #136