refactor(docs): strip residual Phase/Plan setup-history references

Final sweep for setup-process bookkeeping not caught by template-reset-v1.
ADRs drop Plan-N qualifiers; spec collapses the historical 11-phase
migration table; scaffolding guide drops "Phase added" column; comment
prefixes referencing R-numbers in test describes / eslint inline comments
are normalized. Architecture-level rule IDs (R40, R52, E0, J0, etc.) are
preserved where they serve as stable cross-references in ADRs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web-next/next.config.mjs

@@ -16,7 +16,7 @@ const nextConfig = {
 };
 
 export default withSentryConfig(nextConfig, {
-  // R52 — token is build-time only; CI sets SENTRY_AUTH_TOKEN
+  // Token is build-time only; CI sets SENTRY_AUTH_TOKEN.
   silent: process.env.CI !== "true",
   authToken: process.env.SENTRY_AUTH_TOKEN,
   org: process.env.SENTRY_ORG,