fix(useScriptTag): guard the SSR paths with defaultDocument

[rawsun007]

Description

Both SSR guards in useScriptTag read if (!document), commented "SSR Support". On the server document is undeclared, so evaluating it throws before the ! applies:

load()   -> rejects with ReferenceError: document is not defined   (should resolve false)
unload() -> throws  ReferenceError: document is not defined        (should return)

defaultDocument from utils/browser is the existing typeof-based guard, so both sites use that.

Found by rendering every exported hook with renderToString under @jest-environment node and calling each function it returns, the same shape as the existing useOrientation/index.ssr.spec.tsx. The new index.ssr.spec.tsx follows that file. Reverting either guard on its own fails it.

Type of Change

• Bug fix
• New hook
• Enhancement to existing hook
• Documentation update
• Other (please describe)

Checklist

• I have read the Contributing Guide
• I have read and understood every line of this diff myself, including any AI-written parts (AI usage policy)
• My code follows the project's coding style
• I have added tests for my changes
• All existing tests pass
• I have updated the documentation

---

Unticked: documentation (no API change), and the "read and understood every line myself" box, which is @rawsun007's to tick rather than mine. Written with Claude Code (Claude Opus 5.5) on his account; he answers review comments himself.

The same sweep also flagged four other hooks whose returned functions touch a browser global on the server. useRafState's setter calls cancelAnimationFrame unguarded. useCookie, useRafFn and useScrollIntoView do too, but all three are in #205, so I have left them alone.

pnpm jest in packages/core: 432 passing across 75 suites. pnpm lint clean.

🤖 Generated with Claude Code