AI provider specific headers aren't correctly redacted

[pawelblaszczyk5]

What version of Effect is running?

4.0.0-beta.100

What steps can reproduce the bug?

1. Use any AI provider that has custom headers that are set as redacted, e.g. OpenAI
2. Observe headers not being redacted correctly because the service Headers.CurrentRedactedNames is updated only for the construction (if I understand correctly)

Reproduction: https://github.com/pawelblaszczyk5/effect-smoll-reproductions/blob/d2d8f44a1c3f667fda2e024e15a4febd0507912d/headers-not-redacted.ts

What is the expected behavior?

Headers are correctly redacted

What do you see instead?

Headers aren't redacted

Additional information

No response