fix(fetch): preserve Request __sapiom metadata across cloning

[kutluhaneth46]

Summary

• @sapiom/fetch cloned Request inputs with new Request(input, init) before reading __sapiom, so per-request { enabled: false } overrides were silently dropped.
• Read metadata from the source Request before cloning and copy it onto every internal new Request (identity header, authorization, 402 retry).

Fixes #690

Test plan

• sapiom-request.test.ts — reproduces issue [Bug]: @sapiom/fetch loses Request.__sapiom metadata when cloning input #690 shape + clone helpers
• CI (@sapiom/fetch jest)

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