fix: Resolve panic with ElementKeyInt(0): can't use tftypes

[fatmcgav]

Rollback Plan

If a change needs to be reverted, we will publish an updated version of the library.

Changes to Security Controls

Are there any changes to security controls (access controls, encryption, logging) in this pull request? If so, explain.

Description

This commit updates the manifest/morph/scaffold.go logic in order to
resolve a panic encountered when working with Tuple types.

Also adds a new unit test to cover this case.

Disclaimer: This fix and the coresponding test case was generated by
Gemini, and has been reviewed and tested by myself.

Acceptance tests

• Have you added an acceptance test for the functionality being added?
• Have you run the acceptance tests on this branch?

Output from acceptance testing:

$ cd manifest
$ make testacc TESTARGS="-run ^TestKubernetesManifest_StrategicPatch"
go test -count=1 -tags acceptance "./test/acceptance" -v -run ^TestKubernetesManifest_StrategicPatch -timeout 120m
2025/10/15 17:06:15 Testing against Kubernetes API version: v1.34.0
=== RUN   TestKubernetesManifest_StrategicPatch
--- PASS: TestKubernetesManifest_StrategicPatch (8.37s)
PASS
ok      github.com/hashicorp/terraform-provider-kubernetes/manifest/test/acceptance     8.815s

Release Note

Release note for CHANGELOG:

fix: Resolve issue with provider crashing the `kubernetes_manifest` resource when working with complex manifests

References

Fixes: #2778 #2754 plus probably others...

Community Note

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