feat(core): passes controller.signal into the new Request

[jp-knj]

Changes

• What does this change?
  Issue Astro request.signal abort event not called for SSE #12867 demonstrated that SSE streams never fire request.signal on disconnect, so user‐land cleanup (e.g. closing streams, deleting clients) never runs. By wiring up the real HTTP socket’s close event to the AbortSignal, we restore expected semantics:

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Testing

Docs

[changeset-bot]

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Latest commit: 6139c30

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[codspeed-hq]

CodSpeed Performance Report

Merging #13747 will not alter performance

_{Comparing jp-knj:add-signal (6139c30) with main (6935540)}

Summary

✅ 6 untouched benchmarks