[Fix][scala-sttp][circe] Add NaN-tolerant Decoder[Double] for non-finite values

[nikhilsu]

Fixes #23610.

Adds a NaN-tolerant Decoder[Double] to the scala-sttp + circe generator. The default Decoder.decodeDouble rejects the JSON strings "NaN", "Infinity", "-Infinity" - values many servers emit when Jackson encounters non-finite doubles. Generated clients hit DecodingFailure on any response containing such a value.

The new NanTolerantDoubleDecoder is added to AdditionalTypeSerializers so it applies to every generated model's Double fields. Strict numeric parsing stays as the first path; string fallback only handles the three non-finite IEEE 754 values.

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cc @chameleon82 (Scala sttp)

---

Summary by cubic

Adds a NaN-tolerant Decoder[Double] to the scala-sttp generator with circe to accept "NaN", "Infinity", and "-Infinity". Prevents response decoding failures when servers emit these non-finite numbers. Fixes #23610.

• Bug Fixes
  • Added NanTolerantDoubleDecoder in AdditionalTypeSerializers; tries strict numeric first, then string fallback for the three IEEE 754 values.
  • Applies to all generated Double fields.
  • Updated tests and the petstore sample to cover the new decoder.

^{Written for commit 8641a01. Summary will update on new commits.}

[nikhilsu]

@wing328 this is a relatively simple fix targeted only to scala-sttp3 with circe generator.

Do you think you can review and include it as part of v7.22.0 milestone? Thank you!

[cubic-dev-ai]

No issues found across 3 files

[wing328]

cc @clasnake (2017/07), @shijinkui (2018/01), @ramzimaalej (2018/03), @chameleon82 (2020/03), @Bouillie (2020/04) @Fish86 (2023/06)

[wing328]

just merged. thanks for the fix

please test with the latest master when you've time.