test(e2e): Add node-anthropic-send-to-sentry test app (#24856)

An e2e app that uses the Anthropic integration the way a user does and
sends the data to a real Sentry project, per #24748. Same shape as the
OpenAI one in #24824.

**Stacked on #24855.** The `latest` variant needs that fix; this PR
targets its branch and retargets to `develop` once it merges.

**The app.** A plain `Sentry.init` on an express app, preloaded with
`node --import`, no tunnel. The stock `@anthropic-ai/sdk` client talks
to OpenRouter's Anthropic-compatible endpoint. Four routes make one real
request each: a message, a streamed message, one through the
`messages.stream()` helper, and a forced tool use.

**The tests.** Each one reads the request's `gen_ai.chat` span back
through the Sentry API, like the other `*-send-to-sentry` apps, and
checks op, origin, status, model, token usage, and that the prompts and
answers arrived. The helper test also checks there is exactly one
`gen_ai.chat` span, which is what caught the duplicate fixed in #24855.
`@anthropic-ai/sdk` is pinned to 0.63.0, the version the integration
suite uses, and a `(latest)` variant runs the same tests against
`@anthropic-ai/sdk@latest`. Both are optional, like the other
send-to-sentry apps.

Closes #24748

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Co-authored-by: Jan Peer Stöcklmair <jan.peer@sentry.io>