feat(tanstackstart-react): Add server-side route parametrization

[nicohrubec]

Server transactions now use parametrized route names instead of raw URLs. GET /users/123 becomes GET /users/$id, fixing high-cardinality transaction grouping.

The framework provides no way to do this natively, so this is implemented using a build manifest approach that should hopefully work in most cases. Route patterns are extracted from routeTree.gen.ts at build time and presorted by number of static/dynamic segments, then matched against request URLs at runtime in wrapFetchWithSentry.

Closes#18284

[cursor]

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