[nextjs-tracker] Align cache-scope diagnostics with Next.js

## Next.js change

Next.js centralized and rewrote the user-facing errors for `"use cache"`, `"use cache: private"`, and `unstable_cache()`. The diagnostics now consistently include the active route, state the prohibited operation and immediate remediation, and end with a relevant `Learn more:` link. This also makes the `revalidateTag()` errors consistent across rendering, cache scopes, and `generateStaticParams`.

**Commit:** [`e9180ea`](https://github.com/vercel/next.js/commit/e9180eae2afd6794018e206cca2c14adc7fbe1d1)
**PR:** [#94300](https://github.com/vercel/next.js/pull/94300)
**Next.js files changed:** `packages/next/src/server/use-cache/`, `packages/next/src/server/web/spec-extension/`, `packages/next/src/server/app-render/`, and related App Router error tests.

## Why this matters to vinext

vinext implements cache directives, `unstable_cache()`, request APIs, and revalidation. Their validation errors are user-visible compatibility behavior: applications and tooling rely on actionable build/SSR diagnostics, and the redbox should match Next.js when an App Router route is available.

The updated cases include request data (`searchParams`, `headers()`, `cookies()`, `request.url`) inside caches, `connection()` in public or private caches, draft-mode mutation, `cacheTag()` / `cacheLife()` outside cache scopes, invalid private-cache composition, cache-fill timeouts/deadlocks, and `revalidateTag()` during render, cache filling, or `generateStaticParams`.

## Priority

**Low**

## Suggested action

- Audit vinext cache-scope and revalidation error paths against the upstream message templates.
- Include `Route "":` when an App Router route is known, identify the invalid API and correction, and append the matching Next.js documentation URL.
- Consolidate shared message construction where practical so the same error is emitted consistently in dev and production.
- Add focused regression tests for representative request-data, private-cache, and revalidation errors, including route-prefixed output.

Start by comparing vinext’s cache-scope and revalidation error paths with the upstream commit e9180ea and PR #94300. Read Next.js files under packages/next/src/server/use-cache/, packages/next/src/server/web/spec-extension/, packages/next/src/server/app-render/, and the related App Router error tests. Done means representative request-data, private-cache, and revalidation diagnostics consistently include the route when known, remediation, and the matching Learn more link in development and production.

Written by the indexing model from the issue text.