Improve static route error guidance (#99724)
## Summary
- explain that request-time work conflicts with the route's static
requirement without repeating “fully static”
- align the overlay explanations, build messages, and error pages for
route body, `generateMetadata()`, and `generateViewport()` errors
- replace the cookie-specific runtime-data card with short browser-data
pseudocode while preserving its existing docs anchor
- update the affected build-output snapshots
## Verification
- `pnpm jest
packages/next/src/next-devtools/dev-overlay/components/instant/instant-guidance-data.test.ts`
- formatted and linted all changed source, test, and MDX files
- Not run: full package build (the isolated worktree reused an older
dependency install that does not include the latest
`@base-ui-components/react` packages)
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