fix(build): preserve staged prerender routing

[james-elicx]

Part 11 of 16 in the staged CDN adapter stack. Depends on #3150.

Summary

• carries adapter-selected stage routing through prerender path discovery
• starts prerender servers from canonical dist while resolving the executable RSC graph from its configured output root
• keeps manifests and prerendered artifacts canonical under dist/server
• updates the stable concrete-path sidecar without rewriting content-hashed entries or sourcemaps
• keeps Node prerender from evaluating host-only runtime imports

Validation

• focused prerender, custom-output, pool, and production-build tests
• cumulative exact-tip changed-test sweep: 3,461 passed, 2 skipped
• full vp check and vinext package build

Review size

• Implementation: +324 / -91 LOC
• Tests and fixtures: +953 / -71 LOC
• Other (docs, config, lockfile): +0 / -0 LOC
• 21 changed files

Measured against codex/cdn-v2-build-stages after rebasing onto main@a6931c0.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@vinext/cloudflare@3151

npm i https://pkg.pr.new/create-vinext-app@3151

npm i https://pkg.pr.new/@vinext/types@3151

npm i https://pkg.pr.new/vinext@3151

commit: be9d340

[github-actions]

Performance benchmarks

Compared be9d340 against base 01bb5ba using alternating same-runner rounds. Next.js was unchanged and skipped.

0 improved · 0 regressed · 6 within ±1.5%

Scenario	Framework	Baseline	Current	Change
Client bundle size (gzip)	vinext	142.3 KB	142.3 KB	⚫ +0.0%
Client entry size (gzip)	vinext	129.6 KB	129.6 KB	⚫ +0.0%
Dev server cold start	vinext	3.23 s	3.22 s	⚫ -0.5%
Production build time	vinext	3.45 s	3.45 s	⚫ -0.2%
RSC entry closure size (gzip)	vinext	125.6 KB	125.6 KB	⚫ +0.0%
Server bundle size (gzip)	vinext	216.4 KB	216.4 KB	⚫ +0.0%

View detailed results and traces

_{🟢 improvement · 🔴 regression · ⚫ change below 1.5% · paired base/head}

[github-actions]

Example	Preview	Production	Original
app-router-cloudflare	preview	production
pages-router-cloudflare	preview	production
app-router-playground	preview	production	original
realworld-api-rest	preview	production
nextra-docs-template	preview	production
benchmarks	preview	production
hackernews	preview	production	original
workers-cache	preview	production
static-export	preview	production
web	preview	production