feat(web-next): Sentry instrumentation hooks + withSentryConfig + R38 PII test

Adds apps/web-next/instrumentation.ts (server) and instrumentation-client.ts
(browser) hooks, wraps next.config.mjs with withSentryConfig (R52), and adds
the R38 per-app PII scrubber smoke test.

Spec deviation: extend PII_KEY_SUBSTRINGS with "ipaddress" so keys like
ipAddress trigger key-level redaction (tighter posture than the spec's
substring list; existing scrub.test.ts still passes).

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

apps/web-next/package.json

@@ -23,6 +23,7 @@
     "@repo/marketing-pages": "workspace:*",
     "@repo/media": "workspace:*",
     "@repo/navigation": "workspace:*",
+    "@sentry/nextjs": "^10.51.0",
     "@tanstack/react-query": "^5.66.0",
     "@trpc/server": "^11.0.0",
     "inversify": "^6.2.0",