fix(sentry): stop reporting expected notFound/redirect as errors

[sentry]

This PR addresses the issue of Sentry reporting expected TanStack Start control-flow signals (notFound() and redirect()) as unhandled errors.

Problem:
TanStack Start uses throw { isNotFound: true } and throw { isRedirect: true } as control-flow mechanisms to signal 404 states and redirects. Sentry's server-side middleware captures these thrown objects as genuine errors before the application code (e.g., loadDocs's catch block) can handle them. This results in a high volume of false positive error reports in Sentry, obscuring actual issues.

Solution:

1. src/utils/sentry-redaction.ts:
   • Introduced isRouterControlFlow(value) to detect objects with isNotFound: true or isRedirect: true.
   • Created filterSentryEvent(event, hint) which returns null (to drop the event) if hint.originalException is a router control-flow object, otherwise it calls redactByokRequestHeaders(event).
2. src/instrument.server.mjs:
   • Updated the Sentry beforeSend configuration to use the new filterSentryEvent.
3. src/router.tsx:
   • Modified the client-side Sentry beforeSend to also check for isRouterControlFlow(hint?.originalException) and return null early for these events, while preserving existing redaction and ad-tech filtering logic.

This change ensures that Sentry only reports actual errors, improving the signal-to-noise ratio in our error monitoring.

Fixes TANSTACK-COM-4QS

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Status	Name	Latest Commit	Updated (UTC)
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Latest commit: 3c6e2b5

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[tannerlinsley]

Updated this against current main and replaced the property checks with Router’s isNotFound/isRedirect helpers. An actual redirect() result is a Response with options, so the old isRedirect === true check missed it. The regression uses real notFound()/redirect() values, keeps ordinary errors and HTTP 500 responses reportable, and checks that BYOK headers are still removed. Current server initialization settings are preserved. The full pnpm test suite and commit hooks passed: 550 unit tests passed with 4 skipped, 2269 chat tests passed, and 20 desktop tests passed with 1 skipped, plus type and lint checks. New CI is running on 3c6e2b5. The server instrumentation change still needs the required team review before merge.