…closes #4)

- New vinext:use-cache Vite plugin transforms file-level and function-level
  "use cache" directives using @vitejs/plugin-rsc transform utilities
- New cache-runtime.ts with registerCachedFunction() that wraps cached
  functions with serialization, cache key generation, and CacheHandler storage
- cacheLife() and cacheTag() now functional: inside "use cache" functions
  they use AsyncLocalStorage context; at page level they set request-scoped
  ISR revalidation via _cacheLifeRouteMap
- Supports "use cache", "use cache: remote", "use cache: private" variants
- File-level "use cache" on pages handled through ISR (not function wrapping,
  since React elements aren't JSON-serializable)
- 9 new unit tests for cache runtime, 5 new E2E tests for both file-level
  and function-level "use cache"

- Bug cloudflare#2: hybrid build skipped Pages Router pre-rendering when App Router entry
  also present — fix: only bail out on pure App Router builds (no pages entry)
- Bug #1: getOutputPath traversal guard bypassed on Windows by backslash urlPath
  — fix: reject urlPath containing backslashes before posix normalize
- Bug cloudflare#4: double-counting in result.skipped when AbortController fires and
  res.text() throws — fix: replace await res.text() with res.body?.cancel()
- Bug cloudflare#6: dynamic routes without getStaticPaths/generateStaticParams classified
  as 'ssr' — fix: use 'unknown' (skipped for unenumerable params, not SSR APIs)
- Bug cloudflare#3: routes that throw in ssrLoadModule silently omitted from
  routeClassifications — fix: wrap in try/catch, add 'unknown' classification
- Bug cloudflare#5: buildReportRows ignored knownRoutes for API routes — fix: check
  known?.get(route.pattern) first, fall back to 'api'
- Bug cloudflare#7: dead !Array.isArray guard after try/catch in expandDynamicAppRoute
  — remove unreachable branch
- Bug cloudflare#8: middlewareHeaders spread onto 200 pre-rendered response could include
  Location header — fix: filter out 'location' before spreading
- Bug cloudflare#9: configOverride typed as Partial<NextConfig> allows unsafe non-scalar
  fields — narrow to Pick<NextConfig, 'output' | 'trailingSlash'>

… reflect production preview coverage

* Add production coverage for global-error compat

* Address global-error review feedback

* docs: update tracker notes for tests #3 and #4 to reflect production preview coverage